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Song J, Yoon M, Nam T, Ahn S, Chung W, Nah B. SU-GG-T-378: Development of Error Analysis Program for Phase-Based Respiratory Gating Radiation Therapy. Med Phys 2008. [DOI: 10.1118/1.2962130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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102
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Lim Y, Kwak J, Kim D, Shin D, Yoon M, Park S, Kim J, Shin J, Lee D, Lee S, Park S, Cho K. SU-GG-J-11: A Mixture of Microscopic Gold Particles as a Fiducial Marker in Image-Guided Radiation Therapy: Phantom Study. Med Phys 2008. [DOI: 10.1118/1.2961568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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103
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Kim D, Lee S, Lim Y, Kwak J, Park S, Shin D, Yoon M, Park S, Cho K. SU-GG-T-513: The Prediction of Output Factor of Range Modulated Bragg Peak Using Patient and Beam Data. Med Phys 2008. [DOI: 10.1118/1.2962262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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104
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Kim J, Kwak J, Shin D, Yoon M, Park S, Shin J, Lim Y, Kim D, Lee S, Park S, Cho K. SU-GG-T-489: Inhomogeneity Correction On the Proton Beam in Radiotherapy Planning Using Computed Tomography for Head-And-Neck Tumors. Med Phys 2008. [DOI: 10.1118/1.2962238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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105
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Shin K, Moon S, Jang N, Lee D, Yoon M, Park S, Kim J, Yoo H, Park S. Dosimetric Comparison of Four Different External Beam Partial Breast Irradiations: Proton, Tomotherapy, Intensity Modulated and 3D Conformal Radiation Therapy. Int J Radiat Oncol Biol Phys 2007. [DOI: 10.1016/j.ijrobp.2007.07.1197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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106
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Yoon MJ, Boime I, Colgin M, Niswender KD, King SS, Alvarenga M, Jablonka-Shariff A, Pearl CA, Roser JF. The efficacy of a single chain recombinant equine luteinizing hormone (reLH) in mares: induction of ovulation, hormone profiles, and inter-ovulatory intervals. Domest Anim Endocrinol 2007; 33:470-9. [PMID: 17658237 DOI: 10.1016/j.domaniend.2007.06.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2006] [Revised: 05/30/2007] [Accepted: 06/01/2007] [Indexed: 10/23/2022]
Abstract
The objectives of this study were to determine the efficacy of recombinant equine luteinizing hormone (reLH) in shortening the time to ovulation in cycling mares and to determine the effects of treatment on endogenous hormones and inter-ovulatory intervals. In study 1, mares of light horse breeds (3-20 years) were treated with either a vehicle, various doses of reLH, or human chorionic gonadotropin (hCG). Cycling mares were examined by palpation and ultrasound per rectum daily or every 12h from the time of treatment to ovulation. In studies 2 and 3, jugular blood samples were collected daily or every 12h from the time of treatment to ovulation for analysis of LH, follicle stimulating hormone (FSH), estradiol-17beta (E(2)), and progesterone (P(4)) by radioimmunoassays (RIA). Increasing doses of reLH (0.3, 0.6, 0.75, and 0.9 mg) showed increasing effectiveness at inducing ovulation within 48 h of treatment. Treatments with the 0.75 and 0.9 mg doses of reLH resulted in 90% and 80% ovulation rates, which were similar to hCG treatment (85.7%). Except for the early rise in LH after treatment with 0.5, 0.65, and 1.0mg of reLH, hormone profiles appeared to be similar between control and treated cycles. Inter-ovulatory intervals were similar between control and treatment cycles. In conclusion, reLH is a reliable and effective ovulatory agent that does not significantly alter endogenous hormone profiles or affect inter-ovulatory intervals.
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Park S, Shin D, Kwak J, Yoon M, Shin J, Lee S, Kim B, Park S, Cho K. SU-FF-T-289: Measurement of Secondary Neutron Dose for Scattering Modes of Proton Radiotherapy in KNCC. Med Phys 2007. [DOI: 10.1118/1.2760951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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108
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Shin D, Yoon M, Park S, Lee S, Lee S, Lee S, Huh H, Cho K, Shin D. SU-FF-T-412: The Development of Multiple Heterogeneous Head and Neck Phantoms for Quality Assurance of Inhomogeneity Correction Algorithm in the Intensity Modulated Radiotherapy and Conformal Dynamic Arc Radiotherapy. Med Phys 2006. [DOI: 10.1118/1.2241331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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109
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Yoon M, Choe B, Chang H. SU-FF-I-67: Magnetization Transfer After Bee Venom Acupuncture Treatment to Osteoarthritis. Med Phys 2006. [DOI: 10.1118/1.2240747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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110
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Yoon M, Shin D, Park S, Lee S, Kim T, Kim D, Cho K. SU-FF-T-59: A Simple Scoring Method of Dose Homogeneity for IMRT Treatment Planning. Med Phys 2006. [DOI: 10.1118/1.2240987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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111
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Yoon M, Shin J, Shin D, Lee S, Park S, Lee D, Kim J, Pyo H, Shin K, Cho K. SU-FF-T-398: Study of Inhomogeneous Dose Distribution in a Cell Box Due to the X-Ray Scattering Effect. Med Phys 2006. [DOI: 10.1118/1.2241317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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112
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Anandan S, Yoon M. Photocatalytic degradation of Nile red using TiO2-β cyclodextrin colloids. CATAL COMMUN 2004. [DOI: 10.1016/j.catcom.2004.03.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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113
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Anandan S, Yoon M. Photoinduced electron transfer studies of Nile red in the presence of TiO2 colloidal nanoparticles. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2004; 60:885-888. [PMID: 15036099 DOI: 10.1016/s1386-1425(03)00313-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2003] [Revised: 07/02/2003] [Accepted: 07/02/2003] [Indexed: 05/24/2023]
Abstract
Photoinduced electron transfers between Nile red (NR) with TiO2 colloidal nanoparticles are studied using picosecond transient absorption and time resolved fluorescence spectroscopy. The dynamics of electron transfer from the dye molecule to the semiconductor were understood from the transient, and also the formation of conduction band electron and Nile red cation radical were detected.
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114
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Sinal CJ, Yoon M, Gonzalez FJ. Antagonism of the actions of peroxisome proliferator-activated receptor-alpha by bile acids. J Biol Chem 2001; 276:47154-62. [PMID: 11606578 DOI: 10.1074/jbc.m107000200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The peroxisome proliferator-activated receptor-alpha (PPARalpha) is a ligand-activated transcription factor that regulates the expression of a number of genes critical for fatty acid beta-oxidation. Because a number of substrates and intermediates of this metabolic pathway serve as ligand activators of this receptor, homeostatic control of fatty acid metabolism is achieved. Evidence also exists for PPARalpha-dependent regulation of genes encoding critical enzymes of bile acid biosynthesis. To determine whether the primary products of bile acid biosynthesis, cholic acid and chenodeoxycholic acid, were capable of modulating PPARalpha function, a variety of in vivo and in vitro approaches were utilized. Feeding a bile acid-enriched diet significantly reduced the degree of hepatomegaly and induction of target genes encoding enzymes of fatty acid beta-oxidation caused by treatment with the potent PPARalpha ligand Wyeth-14,643. Convergent data from mechanistic studies indicate that bile acids interfere with transactivation by PPARalpha at least in part by impairing the recruitment of transcriptional coactivators. The results of this study provide the first evidence in favor of the existence of compounds, normally found within the body, that are capable of antagonizing the physiological actions of PPARalpha. The impact of PPARalpha antagonism by endogenous bile acids is likely to be limited under normal conditions and to have only minimal effects on bile acid homeostasis. However, during certain pathophysiological states where intracellular bile acid concentrations are elevated, meaningful effects on PPARalpha-dependent target gene regulation are possible.
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115
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Yoon M, Putterill JJ, Ross GS, Laing WA. Determination of the relative expression levels of rubisco small subunit genes in Arabidopsis by rapid amplification of cDNA ends. Anal Biochem 2001; 291:237-44. [PMID: 11401297 DOI: 10.1006/abio.2001.5042] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Multigene families are common in higher organisms. However, due to the close similarities between members, it is often difficult to assess the individual contribution of each gene to the overall expression of the family. In Arabidopsis thaliana, there are four genes encoding the small subunits (SSU) of ribulose-1.5-bisphosphate carboxylase oxygenase (rubisco) whose nucleotide sequences are up to 98.4% identical. In order to overcome the technical limitations associated with gene-specific probes (or primers) commonly used in existing methods, we developed a new gene expression assay based on the RACE (rapid amplification of cDNA ends) technique with a single pair of primers. With this RACE gene expression assay, we were able to determine the relative transcript levels between four Arabidopsis SSU genes. We found that the relative SSU gene expression differed significantly between plants grown at different temperatures. Our observation raises the possibility that an adaptation of rubisco to the environment may be achieved through the specific synthesis of the SSU proteins, which is determined by the relative expression levels between the SSU genes.
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116
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Yoon M, Smith DH, Ward P, Medrano FJ, Aggarwal AK, Linden RM. Amino-terminal domain exchange redirects origin-specific interactions of adeno-associated virus rep78 in vitro. J Virol 2001; 75:3230-9. [PMID: 11238849 PMCID: PMC114116 DOI: 10.1128/jvi.75.7.3230-3239.2001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The unique ability of adeno-associated virus type 2 (AAV) to site-specifically integrate its genome into a defined sequence on human chromosome 19 (AAVS1) makes it of particular interest for use in targeted gene delivery. The objective underlying this study is to provide evidence for the feasibility of retargeting site-specific integration into selected loci within the human genome. Current models postulate that AAV DNA integration is initiated through the interactions of the products of a single viral open reading frame, REP, with sequences present in AAVS1 that resemble the minimal origin for AAV DNA replication. Here, we present a cell-free system designed to dissect the Rep functions required to target site-specific integration using functional chimeric Rep proteins derived from AAV Rep78 and Rep1 of the closely related goose parvovirus. We show that amino-terminal domain exchange efficiently redirects the specificity of Rep to the minimal origin of DNA replication. Furthermore, we establish that the amino-terminal 208 amino acids of Rep78/68 constitute a catalytic domain of Rep sufficient to mediate site-specific endonuclease activity.
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117
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Ward JM, Yoon M, Anver MR, Haines DC, Kudo G, Gonzalez FJ, Kimura S. Hyalinosis and Ym1/Ym2 gene expression in the stomach and respiratory tract of 129S4/SvJae and wild-type and CYP1A2-null B6, 129 mice. THE AMERICAN JOURNAL OF PATHOLOGY 2001; 158:323-32. [PMID: 11141507 PMCID: PMC1850245 DOI: 10.1016/s0002-9440(10)63972-7] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The C57BL/6, 129, and B6,129 mouse strains or stocks have been commonly used to generate targeted mutant mice. The pathology of these mice is not well characterized. In studies of these aging mice, we found high incidences of hyalinosis (eosinophilic cytoplasmic change) in the glandular stomach, respiratory tract, bile duct, and gall bladder of B6,129 CYP1A2-null and wild-type mice as well as in both sexes of the background 129S4/SvJae strain. The gastric lesions of the glandular stomach were found in 95.7% of female CYP1A2-null mice as well as in 45.7% of female 129S4/SvJae animals. The eosinophilic protein isolated from characteristic hyaline gastric lesions was identified as Ym2, a member of the chitinase family. Immunohistochemistry, using rabbit polyclonal antibodies to oligopeptides derived from the Ym1 sequence, detected focal to diffuse reactivity within both normal and abnormal nasal olfactory and respiratory epithelium, pulmonary alveolar macrophages, bone marrow myeloid cells, and the squamous epithelium of the forestomach and epithelium of the glandular stomach. Alveolar macrophages in acidophilic pneumonia, a major cause of death of aging 129 mice, and in mice with the me mutation also were highly immunoreactive. The possible cause of this protein excess in gastric and other lesions and its possible functions are discussed.
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MESH Headings
- Animals
- Blotting, Northern
- Blotting, Western
- Chemotactic Factors, Eosinophil/genetics
- Chemotactic Factors, Eosinophil/metabolism
- Cytochrome P-450 CYP1A2/genetics
- Cytochrome P-450 CYP1A2/metabolism
- Electrophoresis, Polyacrylamide Gel
- Female
- Gastric Mucosa/metabolism
- Gene Expression Regulation
- Hyalin/metabolism
- Lectins/genetics
- Lectins/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred Strains
- Mice, Mutant Strains
- Microscopy, Electron
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Respiratory System/metabolism
- Respiratory System/pathology
- Stomach/pathology
- Stomach/ultrastructure
- Survival Analysis
- beta-N-Acetylhexosaminidases/genetics
- beta-N-Acetylhexosaminidases/metabolism
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118
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Kang HC, Lee BM, Yoon J, Yoon M. Synthesis and Surface-Active Properties of New Photosensitive Surfactants Containing the Azobenzene Group. J Colloid Interface Sci 2000; 231:255-264. [PMID: 11049676 DOI: 10.1006/jcis.2000.7158] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several water-soluble cationic surfactants, 4-alkylazobenzene-4'-(oxy-2-hydroxypropyl)trimethylammonium methylsulfate (AZMS) (AZMS-0, AZMS-1, AZMS-2, AZMS-4, and AZMS-8), containing alkylglycidylether and azoarene have been synthesized with high yields of 63-78% and their surface-active properties have been investigated upon irradiation with UV/vis light. All of the trans-AZMS surfactants are isomerized to cis-trans mixtures containing 92.5% cis isomer by UV light irradiation at 350 nm. The cis isomers in the mixtures are reverted to trans isomers by visible light irradiation (lambda>445 nm). Such photoisomerization induces changes in the surface activity of each surfactant. The critical micelle concentration (cmc) of the trans form of AZMS-8 surfactant is about 1.28x10(-4) mol/l. At the photostationary state, 92.5% of the trans form is changed to the cis form which exhibits a slightly higher cmc (3.41x10(-4) mol/l). The new cmc of AZMS surfactants upon photoisomerization is similar to that of the ideal mixed micellar system. In particular, the ratio of cmc(cis) to cmc(trans) of AZMS derivatives is about 1.87-2.85 which increases proportionally with the chain length of alkyl group. The minimum average area per molecule (A(min)(a/w)) for the trans and cis isomers of AZMS-8 is 0.60 and 0.74 nm(2), respectively. The difference in the A(min)(a/w) may originate from the structural differences in the two isomers. These values are quite different as compared to those of the conventional azobenzene surfactants. Copyright 2000 Academic Press.
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Leem JW, Choi Y, Han SM, Yoon MJ, Sim JY, Leem SW. Conduction block by clonidine is not mediated by alpha2-adrenergic receptors in rat sciatic nerve fibers. Reg Anesth Pain Med 2000; 25:620-5. [PMID: 11097671 DOI: 10.1053/rapm.2000.16160] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND AND OBJECTIVES Clonidine, an alpha(2)-adrenergic agonist, has been shown to prolong local anesthesia. It appears that clonidine by itself produces conduction block by acting on peripheral nerves. However, whether clonidine-induced conduction block is mediated through alpha(2)-adrenergic receptors remains unclear. The purpose of this study was to see if clonidine's nerve-blocking action was through alpha(2)-adrenergic receptors by examining clonidine's action in the presence of alpha(2)-adrenergic antagonists. METHODS The compound action potentials (CAPs) evoked by electrical stimuli were recorded from the isolated rat sciatic nerve in a recording chamber. Conduction block was examined by analyzing CAPs with regard to peak amplitude and time-to-peak in the presence of clonidine alone or clonidine plus alpha(2)-adrenergic antagonist yohimbine or idazoxan. RESULTS Both clonidine and yohimbine produced concentration-dependent, reversible, conduction block. Based on concentration-response relationships, the 50% of effective concentration (EC(50)) were estimated to be 1.61 +/- 0.51 mmol/L (mean +/- SD) for clonidine and 51.4 +/- 27.2 micromol/L for yohimbine. A mixture of equal volumes of 2.07 mmol/L clonidine and 55.6 micromol/L yohimbine produced conduction block to a level close to the mean value between conduction blocks induced by 2.07 mmol/L clonidine alone and 55.6 micromol/L yohimbine alone. Addition of idazoxan, a more specific alpha(2)-adrenergic antagonist than yohimbine, to clonidine was without effect on clonidine-induced conduction block. CONCLUSIONS The results indicated that the mixture of clonidine and yohimbine, in which either drug inhibited impulse conduction, produced conduction block in an additive manner, and that clonidine-induced conduction block was not reversed by coapplication with a specific alpha(2)-adrenergic antagonist idazoxan. These data suggest that clonidine's effects likely depend on mechanisms not mediated by alpha(2)-adrenergic receptors.
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Moir RD, Spann TP, Lopez-Soler RI, Yoon M, Goldman AE, Khuon S, Goldman RD. Review: the dynamics of the nuclear lamins during the cell cycle-- relationship between structure and function. J Struct Biol 2000; 129:324-34. [PMID: 10806083 DOI: 10.1006/jsbi.2000.4251] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The nuclear lamins are members of the intermediate filament (IF) family of proteins. The lamins have an essential role in maintaining nuclear integrity, as do the other IF family members in the cytoplasm. Also like cytoplasmic IFs, the organization of lamins is dynamic. The lamins are found not only at the nuclear periphery but also in the interior of the nucleus, as distinct nucleoplasmic foci and possibly as a network throughout the nucleus. Nuclear processes such as DNA replication may be organized around these structures. In this review, we discuss changes in the structure and organization of the nuclear lamins during the cell cycle and during cell differentiation. These changes are correlated with changes in nuclear structure and function. For example, the interactions of lamins with chromatin and nuclear envelope components occur very early during nuclear assembly following mitosis. During S-phase, the lamins colocalize with markers of DNA replication, and proper lamin organization must be maintained for replication to proceed. When cells differentiate, the expression pattern of lamin isotypes changes. In addition, changes in lamin organization and expression patterns accompany the nuclear alterations observed in transformed cells. These lamin structures may modulate nuclear function in each of these processes.
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121
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Goldman RD, Chou YH, Prahlad V, Yoon M. Intermediate filaments: dynamic processes regulating their assembly, motility, and interactions with other cytoskeletal systems. FASEB J 1999; 13 Suppl 2:S261-5. [PMID: 10619140 DOI: 10.1096/fasebj.13.9002.s261] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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122
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Yoo SK, Yoon M, Park UJ, Han HS, Kim JH, Hwang HJ. A radioimmunoassay method for detection of DNA based on chemical immobilization of anti-DNA antibody. Exp Mol Med 1999; 31:122-5. [PMID: 10551259 DOI: 10.1038/emm.1999.20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
High selectivity provided by biomolecules such as antibodies and enzymes has been exploited during the last two decades for development of biosensors. Of particular importance are efficient immobilization methods for biomolecules in order to preserve their biological activities. In this study, we have evaluated immobilization strategies for an anti-DNA antibody on a self-assembled monolayer of omega-functionalized thiols. The antibody was immobilized via peptide bond formation between the primary amines in the antibody and the carboxyl groups on the self-assembled monolayer. The peptide bond coupling was achieved by activating COOH groups on the surface through N-Hydroxysuccimide (NHS)-ester formation, followed by acylation of NH2 group in the antibody. DNA binding activity of the immobilized antibody was examined by counting beta emission from 35S-labeled DNA.
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Sim JY, Choi Y, Yoon MJ, Lee DM, Leem JW. The peripheral venous pressure changes during non-invasive blood pressure measurement. Can J Anaesth 1999; 46:711-2. [PMID: 10442976 DOI: 10.1007/bf03013973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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124
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Yoon M, Moir RD, Prahlad V, Goldman RD. Motile properties of vimentin intermediate filament networks in living cells. J Cell Biol 1998; 143:147-57. [PMID: 9763427 PMCID: PMC2132819 DOI: 10.1083/jcb.143.1.147] [Citation(s) in RCA: 197] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The motile properties of intermediate filament (IF) networks have been studied in living cells expressing vimentin tagged with green fluorescent protein (GFP-vimentin). In interphase and mitotic cells, GFP-vimentin is incorporated into the endogenous IF network, and accurately reports the behavior of IF. Time-lapse observations of interphase arrays of vimentin fibrils demonstrate that they are constantly changing their configurations in the absence of alterations in cell shape. Intersecting points of vimentin fibrils, or foci, frequently move towards or away from each other, indicating that the fibrils can lengthen or shorten. Fluorescence recovery after photobleaching shows that bleach zones across fibrils rapidly recover their fluorescence. During this recovery, bleached zones frequently move, indicating translocation of fibrils. Intriguingly, neighboring fibrils within a cell can exhibit different rates and directions of movement, and they often appear to extend or elongate into the peripheral regions of the cytoplasm. In these same regions, short filamentous structures are also seen actively translocating. All of these motile properties require energy, and the majority appear to be mediated by interactions of IF with microtubules and microfilaments.
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125
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Prahlad V, Yoon M, Moir RD, Vale RD, Goldman RD. Rapid movements of vimentin on microtubule tracks: kinesin-dependent assembly of intermediate filament networks. J Biophys Biochem Cytol 1998; 143:159-70. [PMID: 9763428 PMCID: PMC2132817 DOI: 10.1083/jcb.143.1.159] [Citation(s) in RCA: 273] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The assembly and maintenance of an extended intermediate filament (IF) network in fibroblasts requires microtubule (MT) integrity. Using a green fluorescent protein-vimentin construct, and spreading BHK-21 cells as a model system to study IF-MT interactions, we have discovered a novel mechanism involved in the assembly of the vimentin IF cytoskeleton. This entails the rapid, discontinuous, and MT-dependent movement of IF precursors towards the peripheral regions of the cytoplasm where they appear to assemble into short fibrils. These precursors, or vimentin dots, move at speeds averaging 0.55 +/- 0.24 micrometer/s. The vimentin dots colocalize with MT and their motility is inhibited after treatment with nocodazole. Our studies further implicate a conventional kinesin in the movement of the vimentin dots. The dots colocalize with conventional kinesin as shown by indirect immunofluorescence, and IF preparations from spreading cells are enriched in kinesin. Furthermore, microinjection of kinesin antibodies into spreading cells prevents the assembly of an extended IF network. These studies provide insights into the interactions between the IF and MT systems. They also suggest a role for conventional kinesin in the distribution of non-membranous protein cargo, and the local regulation of IF assembly.
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Kim JM, Yoon M, Kang I, Kim SS, Ha J. Evidence that acetyl-CoA carboxylase isoforms play different biological roles in H9c2 cardiomyocyte. Biochem Biophys Res Commun 1998; 248:490-6. [PMID: 9703953 DOI: 10.1006/bbrc.1998.8991] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present work was performed to identify the possible roles of acetyl-CoA carboxylase isoforms (ACC-alpha and ACC-beta). Two forms show 70% amino acid identity, but N-terminal regions share no homology, indicating that these may be uniquely related to the specific role of each ACC form. Thus, we investigated whether introduction of the exogenous ACC N-terminus into H9c2 cardiomyocytes that express both ACC forms causes a noticeable change in a specific pathway of fatty acid metabolism. The effect of ACC-alpha N-terminus overexpression was specific to the fatty acid synthesis rate resulting in an 80% induction, whereas overexpression of the ACC-beta N-terminus increased fatty acid oxidation rate 50% without affecting the fatty acid synthesis rate. These results suggest that ACC-alpha and beta are involved in the regulation of fatty acid synthesis and oxidation, respectively, and that the N-terminus plays an important role in the process. We further demonstrated that novel proteins specifically bound to the ACC N-terminus. This interaction may mediate the involvement of each ACC form in different cellular activities.
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Beresford PJ, Jaju M, Friedman RS, Yoon MJ, Lieberman J. A role for heat shock protein 27 in CTL-mediated cell death. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1998; 161:161-7. [PMID: 9647220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
CTL exocytosis of granules containing perforin and granzyme proteases induces apoptotic cell death. Either granzyme A or B can act with perforin to trigger apoptosis. Granzyme B activates a ubiquitous apoptotic cascade induced by caspase cleavage, but the granzyme A pathway is largely unknown. Using affinity chromatography with recombinant mutant inactive granzyme A, we previously isolated two granzyme A-binding proteins, PHAP (putative HLA-associated protein) I and II. PHAP II, a substrate of granzyme A, is degraded within minutes of CTL attack. Two additional cytoplasmic proteins of 27 and 53 kDa bind strongly to the mutant granzyme A column, requiring 6 M urea to elute. Sequencing identified these as the monomer and dimer of hsp27, a small heat shock protein up-regulated by stress and cellular activation. Hsp27 coprecipitates with granzyme A from cytoplasmic lysates and is not a substrate of the enzyme. Hsp27 translocates to the detergent-insoluble fraction of target cells and relocalizes from diffuse cytoplasmic staining to long filamentous fibers, especially concentrated in a perinuclear region, within minutes of CTL attack. Hsp27 may participate in morphologic changes during granule-mediated lysis. Low or absent levels of hsp27 expression in T lymphocytes, even after heat shock, may play a role in CTL resistance to granule-mediated lysis.
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Park CE, Kim SM, Kim JM, Yoon M, Kim JY, Kang I, Kim SS, Ha J. Rapid increase of cytosolic content of acetyl-CoA carboxylase isoforms in H9c2 cells by short-term treatment with insulin and okadaic acid. Exp Mol Med 1998; 30:73-9. [PMID: 9873826 DOI: 10.1038/emm.1998.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Mammalian acetyl-CoA carboxylase (ACC) is present in two isoforms, alpha and beta, both of which catalyze formation of malonyl-CoA by fixing CO2 into acetyl-CoA. ACC-alpha is highly expressed in lipogenic tissues whereas ACC-beta is a predominant form in heart and skeletal muscle tissues. Even though the tissue-specific expression pattern of two ACC isoforms suggests that each form may have a distinct function, existence of two isoforms catalyzing the identical reaction in a same cell has been a puzzling question. As a first step to answer this question and to identify the possible role of ACC isoforms in myogenic differentiation, we have investigated in the present study whether the expression and the subcellular distribution of ACC isoforms in H9c2 cardiac myocyte change so that malonyl-CoA produced by each form may modulate fatty acid oxidation. We have observed that the expression levels of both ACC forms were correlated to the extent of myogenic differentiation and that they were present not only in cytoplasm but also in other subcellular compartment. Among the various tested compounds, short-term treatment of H9c2 myotubes with insulin or okadaic acid rapidly increased the cytosolic content of both ACC isoforms up to 2 folds without affecting the total cellular ACC content. Taken together, these observations suggest that both ACC isoforms may play a pivotal role in muscle differentiation and that they may translocate between cytoplasm and other subcellular compartment to achieve its specific goal under the various physiological conditions.
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Goldman RD, Clement S, Khuon S, Moir R, Trejo-Skalli A, Spann T, Yoon M. Intermediate filament cytoskeletal system: dynamic and mechanical properties. THE BIOLOGICAL BULLETIN 1998; 194:361-363. [PMID: 9664663 DOI: 10.2307/1543113] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Yoon M, Young V, Miller GJ. A Bioctahedral NbIVCluster with Bridging Sulfides: [Nb2(μ-S)2Cl4(thf)4]. Acta Crystallogr C 1997. [DOI: 10.1107/s0108270197004277] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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131
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Lee J, Lee SK, Suh JS, Yoon M, Song JH, Lee CH. Magnetic resonance imaging of the wrist in defining remission of rheumatoid arthritis. J Rheumatol 1997; 24:1303-8. [PMID: 9228129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE To assess the efficacy of magnetic resonance imaging (MRI) in objectively defining a state of remission in rheumatoid arthritis (RA) after treatment. METHODS Ten patients with RA involving the wrist were evaluated before treatment with methotrexate and hydroxychloroquine, and then mean 14 mo later with a followup evaluation. Clinical variables, laboratory measurements, and MRI using various techniques (T1 weighted image, T2 weighted image, fat suppression T2 weighted image, postcontrast T1 weighted image, postcontrast dynamic image, postcontrast 3 dimensional image) were observed. Remission was defined by ACR criteria. MRI changes were observed using 3 variables: extent of synovial proliferation; extent of bone marrow edema; and development of new erosion. In 6 of 10 patients, synovial signal intensity time curve changes at 30 s (E30 ratio) were determined for quantitative assessment of synovitis. RESULTS Four patients achieved remission and 6 did not. All patients in remission showed decrease in extent of synovial proliferation and bone marrow edema with no newly developed erosion after treatment, compared to baseline. Five of 6 patients in nonremission showed newly developed erosions with variable changes in extent of synovial proliferation and bone marrow edema. E30 ratio was determined in 3 patients in the remission group and 3 in the nonremission group, with 48% reduction in the former compared to 9% reduction in the latter. CONCLUSION MRI is feasible for objectively defining remission and assessing the therapeutic effect of antirheumatic drugs; utility of MRI measures in clinical remission criteria remains to be verified.
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Yoon M, Kim YH, Cho DW, Suh IH, Lee JH, Ryu BY, Park JR. 2,3-Diphenylmaleic Anhydride, an Analogue of cis-Stilbene. Acta Crystallogr C 1995. [DOI: 10.1107/s0108270194013892] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Yoon M, Mochrie SG, Zehner DM, Watson GM, Gibbs D. Faceting and the orientational phase diagram of stepped Pt(001) surfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:16702-16720. [PMID: 10010830 DOI: 10.1103/physrevb.49.16702] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Watson GM, Gibbs D, Zehner DM, Yoon M, Mochrie SG. Faceting transformations of the stepped Pt(001) surface. PHYSICAL REVIEW LETTERS 1993; 71:3166-3169. [PMID: 10054874 DOI: 10.1103/physrevlett.71.3166] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Yoon M, Chougule P, Dufresne R, Wanebo HJ. Localized carcinoma of the external ear is an unrecognized aggressive disease with a high propensity for local regional recurrence. Am J Surg 1992; 164:574-7. [PMID: 1463102 DOI: 10.1016/s0002-9610(05)80709-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Management problems in patients with recurrent squamous cell carcinoma (SCC) of the external ear (pinna) have prompted a review of the management and treatment outcomes of patients who present with localized disease. Forty patients were seen over a 15-year period (1972 to 1991). Thirty-six were men, and 4 were women, with an age range from 43 to 93 years (average age: 71 years). Presenting TNM status was stage 0 in 2 patients, stage I in 15 patients, stage II in 13 patients, stage III in 2 patients, stage IV in 4 patients, and unknown stage in 4 patients. Thirty-six patients had clinically negative nodes at presentation (N0), and 4 had palpable nodes (N+). The primary treatment was local excision in 13 patients, Mohs' micrographic surgery in 16 patients, local excision plus external beam radiotherapy in 4 patients, and radical resection (parotidectomy/neck dissection/mastoidectomy) with or without radiotherapy in 5 patients. Two patients with stage IV disease died after diagnosis and prior to treatment, and two other patients with stage IV disease received palliative chemotherapy. Twenty patients developed recurrence from 2 months to 8 years. It included nine local recurrences, eight regional recurrences (parotid/neck/mastoid), and three distant metastases (lung or brain). After treatment of the recurrences in 20 patients, 8 are alive 15 months to 16 years later, 2 patients died of other diseases, and 10 patients died of SCC. The recurrences were managed by reoperation, radiotherapy, or chemotherapy. From the results of this study, we conclude that localized carcinoma of the external ear has a high propensity for local and regional failure and merits more aggressive treatment of the primary lesion and elective treatment of the regional lymph nodes and parotid gland in high-risk patients.
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Harrison LL, Leeper J, Yoon M. Preterm infants' physiologic responses to early parent touch. West J Nurs Res 1991; 13:698-707; discussion 708-13. [PMID: 1759449 DOI: 10.1177/019394599101300603] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Harrison LL, Leeper JD, Yoon M. Effects of early parent touch on preterm infants' heart rates and arterial oxygen saturation levels. J Adv Nurs 1990; 15:877-85. [PMID: 2229683 DOI: 10.1111/j.1365-2648.1990.tb01942.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A descriptive exploratory design was used in this study to evaluate the effects of early parent touch on the heart rates and arterial oxygen (O2) saturation levels of 36 preterm infants. The infants were between 27-33 weeks gestational age at birth, and were free of congenital defects. Infants were videotaped during parent visits on up to three separate occasions during the first month of life. Parents were encouraged to interact with their infants as they usually would, and data on the infants' heart rates and O2 saturation levels were recorded every 6 seconds on a portable computer that was interfaced with the infants' monitors. Mean O2 saturation levels were significantly lower during parent touch than during baseline periods on 45% of the visits, and significantly higher during parent touch periods on 19% of the visits. O2 saturation variability was greater during periods of parent touch, and there were more abnormal O2 saturation values during parent touch than during baseline periods. Mean heart rates during parent touch were significantly lower compared to baseline on 17% of the visits, and were higher during parent touch on 43% of the visits. There were no overall differences in mean heart rates between baseline, parent touch and post-visit classifications, although heart rate variability was greater during periods of parent touch. The results indicate that preterm infants' responses to early parent touch are variable, and suggest that blanket policies that limit parent touch during the early weeks of life may not be appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)
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Becker RS, Chakravorti S, Yoon M. Photochemical and photophysical properties of piroxicam and benoxaprofen in various solvents. Photochem Photobiol 1990; 51:151-4. [PMID: 2333332 DOI: 10.1111/j.1751-1097.1990.tb01696.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Laser flash spectroscopy was used to examine the title compounds. Piroxicam has a triplet transient with a maximum near 450 and a lifetime of 3-21 microseconds depending on the solvent. The relative quantum yield is highly solvent dependent being maximum in toluene and greater than or equal to 14 fold lower in hydrogen bonding solvents. There is another transient which is assigned as a proton transferred ground state transient. Some permanent photoproduct also appears to be produced. Benoxaprofen also has a triplet transient with a maximum near 420 nm with a lifetime of 65 microseconds to greater than or equal to 250 microseconds depending on the solvent. In this case, the relative quantum yield only slightly varies among polar and hydrogen bonding solvents. This is in marked contrast to published data on the fluorescence yield. Some permanent photoproduct appears to be produced.
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Kochevar IE, Yoon M. Photosensitization of methyl linoleate oxidation by tryptophan in peptides. Photochem Photobiol 1983; 37:279-85. [PMID: 6844424 DOI: 10.1111/j.1751-1097.1983.tb04473.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Papasozomenos SC, Yoon M, Crane R, Autilio-Gambetti L, Gambetti P. Redistribution of proteins of fast axonal transport following administration of beta,beta'-iminodipropionitrile: a quantitative autoradiographic study. J Cell Biol 1982; 95:672-5. [PMID: 6183280 PMCID: PMC2112962 DOI: 10.1083/jcb.95.2.672] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Beta,beta'-iminodipropionitrile (IDPN) produces a rearrangement of axoplasmic organelles with displacement of microtubules, smooth endoplasmic reticulum, and mitochondria toward the center and of neurofilaments toward the periphery of the axon, whereas the rate of the fast component of axonal transport is unchanged. Separation of microtubules and neurofilaments makes the IDPN axons an excellent model for study of the role of these two organelles in axonal transport. The cross-sectional distribution of [3H]-labeled proteins moving with the front of the fast transport was analyzed by quantitative electron microscopic autoradiography in sciatic nerves of IDPN-treated and control rats, 6 h after injection of a 1:1 mixture of [3H]-proline and [3H]-lysine into lumbar ventral horns. In IDPN axons most of the transported [3H] proteins were located in the central region with microtubules, smooth endoplasmic reticulum and mitochondria, whereas few or none were in the periphery with neurofilaments. In control axons the [3H]-labeled proteins were uniformly distributed within the axoplasm. It is concluded that in fast axonal transport: (a) neurofilaments play no primary role; (b) the normal architecture of the axonal cytoskeleton and the normal cross-sectional distribution of transported materials are not indispensable for the maintenance of a normal rate of transport. The present findings are consistent with the models of fast transport that envision microtubules as the key organelles in providing directionality and propulsive force to the fast component of axonal transport.
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Roos BA, Lindall AW, Aron DC, Orf JW, Yoon M, Huber MB, Pensky J, Ells J, Lambert PW. Detection and characterization of small midregion parathyroid hormone fragment(s) in normal and hyperparathyroid glands and sera by immunoextraction and region-specific radioimmunoassays. J Clin Endocrinol Metab 1981; 53:709-21. [PMID: 7026586 DOI: 10.1210/jcem-53-4-709] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Walker EB, Yoon M, Song PS. The pH dependence of photosensory responses in Stentor coeruleus and model system. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 634:289-308. [PMID: 6781541 DOI: 10.1016/0005-2728(81)90148-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
1. Live Stentor coeruleus exhibits a substantially red-shifted fluorescence maximum, corresponding to the anionic species of the photoreceptor chromophore. No change was observed in either the absorption or fluorescence excitation spectrum, indicating an efficient deprotonation of the photoreceptor pigment upon excitation by light. 2 Changes in external pH exhibit a dramatic effect on the pulmonary response of Stentor. Phototaxis is specifically inhibited at pH less than 6, with loss of photosensory perception which is restored when the pH is returned to pH greater than 6. 3. Fluorescence changes of 9-aminoacridine in suspensions of live Stentor indicate the generation of a pH gradient upon irradiation with light. Both pH gradient and phototaxis were inhibited by the addition of nigericin and p-tri-fluoromethoxy carbonyl cyanide phenylhydrazone (FCCP). 4. Incorporation of the Stentor photoreceptor protein in to artificial liposomes demonstrates the ability of the system to generate pH gradients across model membranes as monitored by the quenching of 9-aminoacridine fluorescence. The effect of external pH on net proton movement in the model system is strikingly similar to the pH dependent of the liver Stentor, thus lending support for transient proton flux being an important mode of light signal processing for photosensory transduction.
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Roos BA, Yoon M, Cutshaw SV, Kalu DN. Calcium regulatory action of endogenous rat calcitonin demonstrated by passive immunization with calcitonin antibodies. Endocrinology 1980; 107:1320-6. [PMID: 7428674 DOI: 10.1210/endo-107-5-1320] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The calcium regulatory role of calcitonin (CT) in murine physiology was evaluated with a combination of immunological techniques, bioassays, and gland ablation. Passive immunization of rats with neutralizing CT antibodies caused an immediate but transient increase in plasma calcium with a time course similar to that observed in thyroparathyroidectomized animals. In animals fasted during the day and fed at night (1700-0700 h), acutely decreasing endogenous CT (< 100 pg/ml) by thyroparathyroidectomy or by passive immunization with CT antibodies resulted in a greater increase in plasma calcium in the preprandial (1600 h) than in the postprandial inverse correlation between immunoreactive CT and plasma calcium, a known secretagogue for CT. In these animals on a restricted feeding schedule, a sharp preprandial (1600 h) rise in immunoreactive and bioactive CT and a circadian rhythm in plasma calcium were also observed. The onset of the increase in circulating CT preceded the onset of feeding and coincided with or shortly preceded the daily nadir of plasma calcium. These findngs establish that CT has a primary calcium regulatory role in murine physiology. More specifically, they demonstrate that 1) the postthyroparathyroidectomy increase in plasma calcium is due specifically to the loss of CT, 2) passive immunization is a feasible technique for evaluating the actions of endogenous CT, 3) the role of CT in calcium regulation cannot be restricted to that of preventing prandial and postprandial increase in blood calcium, and 4) factors other than calcium must be involved in the control of CT secretion in the nonfed state.
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Roos BA, Yoon MJ, Frelinger AL, Pensky AE, Birnbaum RS, Lambert PW. Tumor growth and calcitonin during serial transplantation of rat medullary thyroid carcinoma. Endocrinology 1979; 105:27-32. [PMID: 446409 DOI: 10.1210/endo-105-1-27] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We have recently reported immunochemical methods for the measurement and purification of rat calcitonin (CT). To identify a convenient source of CT-producing cells for studies of rat CT biosynthesis, we have propagated 16 transplantable series of medullary thyroid carcinoma (MTC) from 2 types of WAG/Rij rat MTC from The Netherlands. Tumor CT concentrations and growth and plasma CT accumulation were studied in successive transplant generations of each MTC series. Although most MTC series maintained characteristic predictable tumor CT levels, some MTC series acquired nearly 90% lower CT levels. While related MTC series tended to maintain similar predictable growth rates, several spontaneous and propagatable increases (up to 5-fold) in tumor growth rates were noted. These increases occurred with and without concomitant decreases in tumor CT. Tumor CT production ranged over 20-fold among these 16 MTC series. Serial plasma CT analyses can be used to estimate tumor growth and CT production in live MTC rats. Using serial plasma CT analyses, we can select for serial transplantation tumors with specific growth and CT characteristics. This should facilitate propagation of MTC series needed for particular studies of CT production and cancer.
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Yoon M. Influence of adaptation level on response pattern and sensitivity of ganglion cells in the cat's retina. J Physiol 1972; 221:93-104. [PMID: 5016997 PMCID: PMC1331322 DOI: 10.1113/jphysiol.1972.sp009741] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
1. The effect of background illumination on response pattern is correlated with its effect on visual sensitivity by analysing post-stimulus time-histograms obtained from single ganglion cells in the cat's retina at various levels of background illumination between zero and 2 x 10(6) photons (wave-length 523 nm).sec(-1).deg(-2) (via 5.7 mm(2) pupil).2. If background illumination did not exceed a critical value, about 10(3) photons (523 nm).sec(-1).deg(-2) (via 5.7 mm(2) pupil), stimulation of the centre of a receptive field resulted in either sustained excitation (i.e. increase in discharge rate) during ;on' and cessation of the excitation at ;off' (on-centre unit), or sustained inhibition (i.e. decrease in discharge rate) during ;on' and cessation of the inhibition at ;off' (off-centre unit). Within this low adaptational level, a ganglion cell maintained its maximum sensitivity regardless of whether the weak background light was presented or not.3. When background level exceeded the critical value up to 2 x 10(6) photons (523 nm).sec(-1).deg(-2), however, the simple, sustained responses changed into compound responses with two transient components of opposite polarities, either excitation at ;on' and inhibition at ;off' (on-centre unit), or inhibition at ;on' and excitation at ;off' (off-centre unit), and also the sensitivity began to decrease as the background increased, approximately obeying Weber's law.4. It is suggested that a ganglion cell gives simple-sustained response when its gain control mechanism remains inactive at a low background illumination below a critical level, whereas it gives compound-transient response when its gain control mechanism becomes active as background illumination exceeds the critical value.
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Yoon M. Reorganization of retinotectal projection following surgical operations on the optic tectum in goldfish. Exp Neurol 1971; 33:395-411. [PMID: 5124957 DOI: 10.1016/0014-4886(71)90031-8] [Citation(s) in RCA: 128] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Barlow HB, Levick WR, Yoon M. Responses to single quanta of light in retinal ganglion cells of the cat. Vision Res 1971; Suppl 3:87-101. [PMID: 5293890 DOI: 10.1016/0042-6989(71)90033-2] [Citation(s) in RCA: 210] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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