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Kempf DJ, Marsh KC, Denissen JF, McDonald E, Vasavanonda S, Flentge CA, Green BE, Fino L, Park CH, Kong XP. ABT-538 is a potent inhibitor of human immunodeficiency virus protease and has high oral bioavailability in humans. Proc Natl Acad Sci U S A 1995; 92:2484-8. [PMID: 7708670 PMCID: PMC42242 DOI: 10.1073/pnas.92.7.2484] [Citation(s) in RCA: 410] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Examination of the structural basis for antiviral activity, oral pharmacokinetics, and hepatic metabolism among a series of symmetry-based inhibitors of the human immunodeficiency virus (HIV) protease led to the discovery of ABT-538, a promising experimental drug for the therapeutic intervention in acquired immunodeficiency syndrome (AIDS). ABT-538 exhibited potent in vitro activity against laboratory and clinical strains of HIV-1 [50% effective concentration (EC50) = 0.022-0.13 microM] and HIV-2 (EC50 = 0.16 microM). Following a single 10-mg/kg oral dose, plasma concentrations in rat, dog, and monkey exceeded the in vitro antiviral EC50 for > 12 h. In human trials, a single 400-mg dose of ABT-538 displayed a prolonged absorption profile and achieved a peak plasma concentration in excess of 5 micrograms/ml. These findings demonstrate that high oral bioavailability can be achieved in humans with peptidomimetic inhibitors of HIV protease.
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277
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McCauley LD, Park CH, Lan NC, Tomich JM, Shively JE, Gee KW. Benzodiazepines and peptides stimulate pregnenolone synthesis in brain mitochondria. Eur J Pharmacol 1995; 276:145-53. [PMID: 7781684 DOI: 10.1016/0014-2999(95)00036-k] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Mitochondria isolated from rat brain were found to cleave cholesterol to produce pregnenolone, the precursor for hormonal steroids, at a mean rate of 21.0 pmol pregnenolone.mg protein-1.min-1. This rate-limiting step in steroidogenesis was significantly stimulated by PK 11195 (1-(2-chlorophenyl)-N-methyl-(1-methylpropyl)-3-isoquinoline carboxamide) and Ro5 4864 (4'-chlorodiazepam), ligands which bind to peripheral benzodiazepine receptors with high affinity. Low-affinity ligands for the peripheral benzodiazepine receptor such as Ro15 1788 (ethyl-8-fluoro-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5 alpha][1,4] benzo-3-carboxylate) and clonazepam had no significant effect on the rate of pregnenolone synthesis. Furthermore, the rank order of potency of these compounds as inhibitors of [3H]Ro5 4864 binding was identical to the rank order for steroid production. Since the 86-amino acid peptide diazepam binding inhibitor is also thought to bind to the peripheral benzodiazepine receptor, four fragments of this peptide, a random sequence and steroidogenesis activator peptide were also evaluated for their ability to interact with peripheral benzodiazepine receptors and to stimulate steroidogenesis in rat brain mitochondria. Steroidogenesis activator peptide and two fragments of diazepam binding inhibitor significantly stimulated pregnenolone biosynthesis. In contrast to the peripheral benzodiazepine receptor ligands, no correlation between peptide potency in displacing [3H]Ro5 4864 binding and steroidogenesis was observed.
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278
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Park CH, Mu D, Reardon JT, Sancar A. The general transcription-repair factor TFIIH is recruited to the excision repair complex by the XPA protein independent of the TFIIE transcription factor. J Biol Chem 1995; 270:4896-902. [PMID: 7876263 DOI: 10.1074/jbc.270.9.4896] [Citation(s) in RCA: 163] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Recent studies have revealed that the general transcription factor TFIIH is also a general excision repair factor which, along with several other proteins, is required for transcription-independent excision reaction. As a general transcription factor, TFIIH is recruited to RNA polymerase II-promoter complex by another general transcription factor called TFIIE. We were interested in knowing whether TFIIE is also involved in recruiting TFIIH to the excision repair complex. We found that cell-free extract depleted of TFIIE carried out excision repair at a normal rate, leading us to conclude that TFIIE is not involved in recruiting TFIIH to the damage site and has no role in general excision repair. In contrast, the human damage recognition protein XPA specifically binds to TFIIH and apparently recruits it to the damage site. The carboxyl-terminal half of XPA is responsible for specific interaction with TFIIH. The C261S/C264S mutant of XPA bound the ERCC1-XPF complex normally, but failed to bind TFIIH and failed to complement an XP-A mutant cell-free extract indicating that the XPA-TFIIH interaction is essential to effecting the excision reaction. Interestingly, XPA also binds to the p34 subunit of TFIIE specifically and in competition with the p56 subunit of TFIIE. This latter interaction has no apparent role in general excision repair but may be relevant in the transcription-coupled repair reaction.
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Abstract
Hyperfunctioning thyroid adenomas causing thyrotoxicosis (Plummer's disease) is not an uncommon cause of hyperthyroidism in the elderly. Most commonly, the adenoma appears as a so-called "hot" nodule on thyroid scintigraphy causing suppression (i.e., nonvisualization) of the remainder of the gland. This report describes a case of Plummer's disease in an elderly patient in whom the toxic nodule primarily responsible for causing the hyperthyroidism became scintigraphically apparent at 96 hours after I-131 therapeutic ablation.
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281
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Richard MD, Park CH. Tc-99m MIBI uptake secondary to pulmonary interstitial fibrosis in progressive systemic sclerosis. Clin Nucl Med 1995; 20:256-8. [PMID: 7750221 DOI: 10.1097/00003072-199503000-00014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Pulmonary uptake of Tc-99m MIBI in a patient with progressive systemic sclerosis (PSS, diffuse scleroderma) is described. Nonspecific alveolitis, active interstitial fibrosis pulmonary hypertension, and specific uptake by the fibroblasts in patients with PSS are possible mechanisms of Tc-99 MIBI uptake observed.
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282
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Israel HL, Park CH, Kane GC. 67Gallium scans in Löfgren's syndrome. SARCOIDOSIS 1995; 12:58-60. [PMID: 7617978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Comparison of 67Gallium scans of head and neck showed no significant difference in intensity of uptake between patients with Löfgren's syndrome and sarcoidosis patients with similar chest x rays having other modes of onset. Uptake was the same in the 12 white and 18 black patients studied. Thus, the increased bronchoaveolar lavage lymphocytosis which has been shown to be a feature of Löfgren's syndrome is not paralleled by gallium uptake. Gallium scores had no predictive value regarding outcome showing no significant difference between 13 patients who recovered within a year and 15 patients who developed chronic disease. The outcome was more favorable in white patients and in those whose onset was with Löfgren's syndrome.
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283
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Mu D, Park CH, Matsunaga T, Hsu DS, Reardon JT, Sancar A. Reconstitution of human DNA repair excision nuclease in a highly defined system. J Biol Chem 1995; 270:2415-8. [PMID: 7852297 DOI: 10.1074/jbc.270.6.2415] [Citation(s) in RCA: 382] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Xeroderma pigmentosum is a hereditary disease caused by defective DNA repair. Somatic cell genetics and biochemical studies with cell-free extracts indicate that at least 16 polypeptides are required to carry out the repair reaction proper, i.e. the removal of the lesion from the DNA by the dual incisions of the damaged strand. To find out if these proteins are necessary and sufficient for excision repair, they were obtained at a high level of purity in five fractions. The mixture of these five fractions reconstituted the excision nuclease (excinuclease) activity. Using the reconstituted excinuclease, we found that the excised fragment remains associated with the post-incision DNA-protein complex, suggesting that accessory proteins are needed to release the excised oligomer.
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Cobos E, Keung YK, Morgan D, Park CH. Successful engraftment using allogeneic peripheral blood progenitor cells in a patient with primary bone marrow graft failure. JOURNAL OF HEMATOTHERAPY 1995; 4:37-40. [PMID: 7757398 DOI: 10.1089/scd.1.1995.4.37] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
G-CSF-mobilized peripheral blood progenitor cells (PBPC) were utilized in a patient who failed to engraft after an unmanipulated HLA-matched allogeneic bone marrow transplant. Marrow engraftment occurred after repeated conditioning with high-dose cyclophosphamide and PBPC infusion. Severe graft-versus-host disease (GVHD) developed shortly after marrow engraftment. The role of PBPC in allogeneic transplant, the associated potential risk of GVHD, and the necessity of reconditioning before stem cell reinfusion are discussed.
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285
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King DM, Shen Z, Dessau DS, Marshall DS, Park CH, Spicer WE, Peng JL, Li ZY, Greene RL. Observation of a saddle-point singularity in Bi2(Sr0.97Pr0.03)2CuO6+ delta and its implications for normal and superconducting state properties. PHYSICAL REVIEW LETTERS 1994; 73:3298-3301. [PMID: 10057341 DOI: 10.1103/physrevlett.73.3298] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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286
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Tighe DA, Hutchinson HG, Park CH, Chung EK, Fischman DL, Raichlen JS. False-positive reversible perfusion defect during dobutamine-thallium imaging in left bundle branch block. J Nucl Med 1994; 35:1989-91. [PMID: 7989982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
In the presence of pre-existing left bundle branch block (LBBB) exercise stress thallium scans have been associated with false-positive septal and apical perfusion abnormalities. Recent reports have documented a lower incidence of false-positive septal perfusion defects when pharmacologic agents such as dipyridamole or adenosine are utilized in patients with LBBB. Dobutamine, a synthetic catecholamine, is being used with increasing frequency in combination with perfusion agents for the diagnosis of coronary artery disease in patients unable to achieve an adequate exercise workload. Because the positive inotropic and chronotropic actions of doubtamine are similar to the physiologic effects of treadmill exercise, it is conceivable that false-positive perfusion abnormalities will be observed in patients with pre-existing LBBB undergoing dobutamine perfusion imaging. We describe a patient with underlying LBBB who underwent dobutamine thallium imaging which revealed septal and periapical defects. Subsequent coronary angiography showed these abnormalities to be false-positive. It is concluded that septal and periapical perfusion abnormalities during dobutamine thallium imaging may be false-positive and should be interpreted cautiously.
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287
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Fabian CJ, Kimler BF, McKittrick R, Park CH, Lin F, Krishnan L, Jewell WR, Osborne CK, Martino S, Hutchins LF. Recruitment with high physiological doses of estradiol preceding chemotherapy: flow cytometric and therapeutic results in women with locally advanced breast cancers--a Southwest Oncology Group study. Cancer Res 1994; 54:5357-62. [PMID: 7923165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
One theoretical method of increasing chemotherapeutic efficacy in breast cancer is to temporarily increase the number of tumor cells in cycle through hormonal recruitment prior to initiation of chemotherapy. In an effort to determine when and if this could be reliably accomplished, 50 women with locally advanced and/or metastatic breast cancer with known estrogen receptor (ER) status were entered into a serial breast biopsy study designed to measure increases in S-phase fraction (SPF) and proliferative index (PI; S + G2 + M) following administration of a high physiological dose of estrogen via estradiol vaginal suppositories prior to chemotherapy. Blood levels of estradiol were maintained in a range (0.5-5 nM) known to increase SPF in vitro. Compliance with suppository administration was monitored by serial blood sampling. Tumors were sampled at 0, 24, 48, 72, and/or 96 h. Thirty-one ER-positive and 9 ER-negative women had evaluable baseline biopsies and at least 1 subsequent biopsy. An increase was seen for SPF in 20 (69%) and for PI in 23 (79%) of 29 ER-positive patients at 48 h after estrogen initiation (95% confidence intervals, 49-85% for SPF and 60-92% for PI); similar increases were seen at 72 h. Median baseline SPF and PI values in ER-positive patients for whom increases were noted at 48 h were 6.2 and 8.5%, respectively. The median relative increases in these patients were 170 and 100%, respectively, at 48 h. The increases observed at 24 h in 4 (SPF) and 6 (PI) of the 9 ER-negative patients could have occurred by chance alone. Twenty-five of the 28 locally advanced (T4 and/or N2-3) patients achieved a complete response during combined modality treatment (estradiol-chemotherapy, mastectomy, and radiation). At a minimum follow-up time of 42 months, estimated 5-year progression-free and overall survivals are 30 and 49%, respectively, with a median time to progression of 35 months. Twenty-two women had metastatic disease (19 also had locally advanced disease). Thirteen had a complete or partial response, with a median duration of 12 months. Median progression-free and over-all survival times for all metastatic patients are 4 and 17 months, respectively. Estimated 5-year survival for metastatic disease patients is 27%. A high physiological dose of estrogen administered to patients with locally advanced ER-positive tumors can reliably increase the tumor SPF and PI within 48 h.(ABSTRACT TRUNCATED AT 400 WORDS)
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Abstract
Stringent quality control cannot be overemphasized in performing SPECT. SPECT artifacts related to camera uniformity, center of rotation, and the patient's motion are well recognized. In this communication, another rare cause of a SPECT artifact related to a triad system is reported. A triple-headed SPECT system was accidentally equipped with two ultrahigh-resolution collimators and a general all-purpose collimator during a brain SPECT study, causing a false cerebral blood flow defect.
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289
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Cho WH, Park CH, Lee SH, Park SB, Kim HC. Acute rejection after living donor renal transplantation. Transplant Proc 1994; 26:1995-6. [PMID: 8066647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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290
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Kim HC, Park SB, Lee SH, Cho WH, Park CH, Park KK. Analysis of 214 percutaneous allograft renal biopsies. Transplant Proc 1994; 26:2197-8. [PMID: 8066719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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291
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Park CH, Ryu DS, Kim KS, Cho WH, Park SB, Kim HC. Urologic morbidity of vesicoureteral reflux in the renal transplantation candidate. Transplant Proc 1994; 26:2189-90. [PMID: 8066716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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292
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Park CH, Ryu DS, Kim KS, Cho WH, Park SB, Kim HC. Vesicoureteric reflux following renal transplantation: significance and risks. Transplant Proc 1994; 26:2191-2. [PMID: 8066717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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293
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Park SB, Kim HC, Lee SH, Cho WH, Park CH. Evolution of serum ferritin levels in renal transplant recipients with severe iron overload. Transplant Proc 1994; 26:2054-5. [PMID: 8066668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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294
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Kim HC, Park SB, Lee SH, Cho WH, Park CH, Park KK. Analysis of 214 percutaneous renal allograft biopsies. Transplant Proc 1994; 26:1997-8. [PMID: 8066648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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295
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Kim HC, Park SB, Lee SH, Park KK, Park CH, Cho WH. Proteinuria in renal transplant recipients: incidence, cause, and prognostic importance. Transplant Proc 1994; 26:2134-5. [PMID: 8066696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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296
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Park CH, Nishimura K, Kitano M, Okamoto Y, Ban T. Right ventricular performance is impaired by full assist of left heart bypass. Analysis of right ventricular performance against change in afterload in heart failure models. ASAIO J 1994; 40:M303-8. [PMID: 8555529 DOI: 10.1097/00002480-199407000-00013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The purpose of this study was to assess right ventricular (RV) performance during left heart bypass (LHB) and to determine the optimum LHB driving conditions to preserve RV performance. LHB was established with a centrifugal pump in eight mongrel dogs weighing 11-19 kg. Failing heart models were induced by normothermic aortic clamping for 20 min. RV volume was measured by a conductance catheter, and RV performance was evaluated by two parameters. One was the slope of the RV end-systolic pressure-volume relationship (ESPVR) as a load independent index, and the other was the peak RV pressure (PRVP)-RV stroke volume (RVSV) relationship as a "force-velocity relationship." These parameters were measured during varying assist ratios of LHB at 0% to 100% of pulmonary artery flow, and varying afterload as induced by bilateral intrapulmonary balloon inflation. In failing hearts, RV ESPVR showed an inverse correlation, with the assist ratio of LHB significantly decreasing from 4.23 +/- 1.35 (mmHg/ml) to 3.52 +/- 1.30 (mmHg/ml; P < 0.05) after 100% LHB assist. The correlation between PRVP and RVSV also was inversely linear, the slope of this correlation becoming significantly steeper after 100% LHB assist compared to that without LHB (-0.131 +/- 0.042 vs. -0.051 +/- 0.038, P < 0.005). These two slopes intersected, and this intersection was considered the critical point of afterload above which RVSV was decreased by LHB compared to that without LHB. In addition, reducing the assist ratio made the slope of the PRVP-RVSV correlation significantly more gentle (70%: -0.072 +/- 0.037 vs. 100%: -0.131 +/- 0.042, P < 0.05), with the intersection of the two slopes shifting rightward (i.e., higher afterload). Consequently, the critical level of afterload at 70% LHB assist was significantly higher than that at 100% LHB assist (70%: 38.1 +/- 6.9 vs. 100%: 29.2 +/- 6.8, P < 0.05). Therefore, RV performance against afterload was improved by reducing the assist ratio of LHB. This study demonstrates that RV performance is impaired by full LHB assist if the RV afterload is above the critical level, and that reducing the assist ratio may improve RV performance against afterload.
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298
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Park CH, Chadi DJ. First-principles study of the atomic reconstructions of ZnSe(100) surfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:16467-16473. [PMID: 10010798 DOI: 10.1103/physrevb.49.16467] [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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299
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Kim SM, Park CH, Intenzo CM, McEwan JR. Findings of diffuse lymphadenitis secondary to rheumatoid arthritis and synovitis on Tc-99m labeled leukocyte scan. Clin Nucl Med 1994; 19:549-50. [PMID: 8062481 DOI: 10.1097/00003072-199406000-00021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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300
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Park CH, Sancar A. Formation of a ternary complex by human XPA, ERCC1, and ERCC4(XPF) excision repair proteins. Proc Natl Acad Sci U S A 1994; 91:5017-21. [PMID: 8197175 PMCID: PMC43921 DOI: 10.1073/pnas.91.11.5017] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The xeroderma pigmentosum complementation group A (XP-A) protein, XPA, has recently been expressed in Escherichia coli in a soluble and fully functional form. An affinity column was prepared by linking the XPA protein to a solid support. When HeLa cell-free extract capable of excision repair was applied to the column, > 99.9% of the proteins were in the flow-through. However, the flow-through fraction lacked excision activity. The activity was restored by adding the high salt (1 M KCl) eluate of the column to the flow-through fraction. The XPA protein-bound fraction was tested for specific proteins by an in vitro complementation assay with a panel of cell-free extracts from DNA repair-deficient human and rodent cell lines. The XPA-bound fraction complemented cell-free extracts of excision repair cross-complementing 1 (ERCC-1), ERCC-4 (XP-F), and XP-A mutants. We conclude that the XPA damage recognition protein makes a ternary complex with the ERCC1/ERCC4(XPF) heterodimer with a potential nuclease function.
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