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Ho C. Extracorporeal shock wave treatment for chronic lateral epicondylitis (tennis elbow). ISSUES IN EMERGING HEALTH TECHNOLOGIES 2007:1-4. [PMID: 17302021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
(1) Electrohydraulic, electromagnetic, or piezoelectric devices are used to translate energy into acoustic waves during extracorporeal shock wave treatment (ESWT) for chronic lateral epicondylitis (CLE) of the elbow (elbow tendonitis or tennis elbow). These waves may help to accelerate the healing process via an unknown mechanism. (2) Results from randomized controlled trials have been conflicting. Half of the studies showed statistically significant improvement in pain in the treatment group, and half of the studies had data showing no benefit over placebo for any measured outcomes. (3) Limited evidence shows that ESWT is cheaper than arthroscopic surgery, open surgery, and other conservative therapies, such as steroid infiltrations and physiotherapy, that continue for more than six weeks. (4) The lack of convincing evidence regarding its effectiveness does not support the use of ESWT for CLE.
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Ho C. Extracorporeal shock wave treatment for chronic rotator cuff tendonitis (shoulder pain). ISSUES IN EMERGING HEALTH TECHNOLOGIES 2007:1-4. [PMID: 17302022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
(1) Electrohydraulic, electromagnetic, or piezoelectric devices are used to translate energy into acoustic waves during extracorporeal shock wave treatment (ESWT) for chronic rotator cuff tendonitis (shoulder pain). The acoustic waves may help to accelerate the healing process of chronic rotator cuff tendonitis via an unknown mechanism. (2) ESWT, which is performed as an outpatient procedure, is intended to alleviate the pain due to chronic rotator cuff tendonitis. (3) Limited evidence from a German study indicates that the cost of ESWT for rotator cuff tendonitis is one-fifth to one-seventh the cost of surgical treatment, with longer recovery time and time off work in the surgical treatment group accounting for about two-thirds of the overall cost. (4) The evidence reviewed for this bulletin supports the use of high-energy ESWT for chronic calcific rotator cuff tendonitis, but not for non-calcific rotator cuff tendonitis. High-quality RCTs with larger sample sizes are needed to provide stronger evidence.
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Ho C. Extracorporeal shock wave treatment for chronic plantar fasciitis (heel pain). ISSUES IN EMERGING HEALTH TECHNOLOGIES 2007:1-4. [PMID: 17302019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
(1) Electrohydraulic, electromagnetic, or piezoelectric devices are used to translate energy into acoustic waves during extracorporeal shock wave treatment (ESWT) for chronic plantar fasciitis (or heel pain). These waves may help to accelerate the healing process via an unknown mechanism. (2) ESWT, which is performed as an outpatient procedure, is intended to alleviate the pain due to chronic plantar fasciitis. (3) Results from randomized controlled trials have been conflicting. Six trials reported data that favour ESWT over placebo or conservative treatment for efficacy outcomes, while three trials showed no significant difference between the ESWT group and the placebo group. (4) The lack of convergent findings from randomized trials of ESWT for chronic plantar fasciitis suggests uncertainty about its effectiveness. The evidence reviewed in this bulletin does not support the use of this technology for this condition.
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Ho C, Eisen D, Beckett LA, Luciw P, Gumerlock PH, Gandara DR, Davies AM. Escalating weekly doses of cetuximab: A phase I trial in advanced solid tumors. J Clin Oncol 2006. [DOI: 10.1200/jco.2006.24.18_suppl.13012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
13012 Background: Cetuximab, an IgG1 monoclonal antibody directed against the epidermal growth factor receptor (EGFR), is FDA-approved at a 400 mg/m2 loading dose, followed by 250 mg/m2 weekly maintenance. Clinical activity of cetuximab has been reported to correlate with grade of skin toxicity, and skin toxicity is reported to increase with increasing dose. We therefore examined the safety and feasibility of escalating weekly cetuximab doses. We hypothesized that increased dose would correlate with rash severity as a surrogate for tumor response. Methods: Four dose levels were tested: cetuximab loading 400 mg/m2 and 250,300,350,400 mg/m2 weekly maintenance. Dose limiting toxicity (DLT) was defined as: grade 4 platelets, grade 3 platelets with bleeding, febrile neutropenia, grade 4 cutaneous toxicity, grade 3 cutaneous toxicity necessitating holding cetuximab for > 4 weeks or any other grade ≥ 3 non-hematologic toxicity. Rash was evaluated using two additional validated dermatology methods: acne lesion counting and global acne grading scale (Int J Derml.1997;36:416–18, J Am Acad Derm.1996;35:559–65, Arch Derm.1982;118:23–25). Results: Twelve patients with advanced solid tumors were treated, including 3 H&N, 2 pancreas, 2 breast, 2 lung, 2 colorectal and 1 bladder. Patient characteristics: age range 44–84, median 62; gender: 10 M; KPS ≥80/<80=7/5; prior chemo ≤1:>1=5:7; median cycles 2 (1–8). Treatment was generally well tolerated. There were no DLTs. The most common grade 3/4 toxicities were acneiform rash (1) and lymphopenia (2). The majority of patients (6) had a Grade 2 rash. In 10 evaluable patients, there were no responses; 3 patients had stable disease. Correlative science studies are ongoing evaluating EGFR expression and polymorphisms, pEGFR, pMAPK, pAKT, Ki67, p27 levels and K-ras mutations. Conclusions: 1) Cetuximab 400 mg/m2 loading dose and 400 mg/m2 weekly maintenance is feasible and well tolerated. Doses up to 400 mg/m2 did not portend increased toxicity and a MTD was not reached on this schedule. 2) Grade of rash did not increase with increasing doses of weekly cetuximab in this limited population. 3) To date, cetuximab has not demonstrated RECIST response in this cohort of pretreated patients with solid tumors. 20 additional patients are being evaluated at the highest dose level. No significant financial relationships to disclose.
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Viljoen A, Walker KS, Ho C, Twomey PJ. Analysis of cerebrospinal fluid for suspected subarachnoid haemorrhage is improved by built-in spectrophotometer software. Clin Mol Pathol 2006; 59:667. [PMID: 16731614 PMCID: PMC1860386 DOI: 10.1136/jcp.2005.028191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Heng JB, Aksimentiev A, Ho C, Marks P, Grinkova YV, Sligar S, Schulten K, Timp G. The electromechanics of DNA in a synthetic nanopore. Biophys J 2006; 90:1098-106. [PMID: 16284270 PMCID: PMC1367096 DOI: 10.1529/biophysj.105.070672] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Accepted: 10/17/2005] [Indexed: 11/18/2022] Open
Abstract
We have explored the electromechanical properties of DNA on a nanometer-length scale using an electric field to force single molecules through synthetic nanopores in ultrathin silicon nitride membranes. At low electric fields, E < 200 mV/10 nm, we observed that single-stranded DNA can permeate pores with a diameter >/=1.0 nm, whereas double-stranded DNA only permeates pores with a diameter >/=3 nm. For pores <3.0 nm diameter, we find a threshold for permeation of double-stranded DNA that depends on the electric field and pH. For a 2 nm diameter pore, the electric field threshold is approximately 3.1 V/10 nm at pH = 8.5; the threshold decreases as pH becomes more acidic or the diameter increases. Molecular dynamics indicates that the field threshold originates from a stretching transition in DNA that occurs under the force gradient in a nanopore. Lowering pH destabilizes the double helix, facilitating DNA translocation at lower fields.
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Hwang P, Liu B, Ho C. Transorbital Eyebrow Approach for Intracranial Aneurysms. Skull Base 2005. [DOI: 10.1055/s-2005-916511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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208
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Farmer MR, Levine E, Ho C, Mishra G, Melin S, Lovato J, Geisinger K, Oaks T, Clark P, Blackstock AW. Pre-operative hyperfractionated radiotherapy and concurrent 5-FU/cisplatin for locally advanced esophageal cancer - the impact of 18-F-fluoro-deoxy-D-glucose (FDG) positron emission tomography staging. J Clin Oncol 2005. [DOI: 10.1200/jco.2005.23.16_suppl.4074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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209
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Lee C, Hong J, Ho C, Chao T. SU-FF-J-111: Correlation of Target Movement, Diaphragm Motion and External Sensor Signals for Respiratory-Gated Hepatoma Radiotherapy Using TACE as a Target Indicator. Med Phys 2005. [DOI: 10.1118/1.1997657] [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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210
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Taylor S, Ho C, Hu F, Barnett J, Melosky B. Anemia and FOLFOX chemotherapy for colorectal carcinoma. J Clin Oncol 2005. [DOI: 10.1200/jco.2005.23.16_suppl.3684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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211
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Ho C, O’Reilly S, Ng K, Gill S. Population-based analysis of patients with advanced colorectal cancer: The impact of age on treatment and outcomes. J Clin Oncol 2005. [DOI: 10.1200/jco.2005.23.16_suppl.3614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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212
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Rajaram D, Burnstein RA, Chakravorty A, Chan A, Chen YC, Choong WS, Clark K, Dukes EC, Durandet C, Felix J, Gidal G, Gu P, Gustafson HR, Ho C, Holmstrom T, Huang M, James C, Jenkins CM, Kaplan DM, Lederman LM, Leros N, Longo MJ, Lopez F, Lu LC, Luebke W, Luk KB, Nelson KS, Park HK, Perroud JP, Rubin HA, Teng PK, Volk J, White CG, White SL, Zyla P. Search for the lepton-number-violating decay Xi(-)-->pmu(-)mu(-). PHYSICAL REVIEW LETTERS 2005; 94:181801. [PMID: 15904358 DOI: 10.1103/physrevlett.94.181801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2004] [Indexed: 05/02/2023]
Abstract
A sensitive search for the lepton-number-violating decay Xi(-)-->pmu(-)mu(-) has been performed using a sample of approximately 10(9) Xi(-) hyperons produced in 800 GeV/c p-Cu collisions. We obtain B(Xi(-)-->pmu(-)mu(-))<4.0x10(-8) at 90% confidence, improving on the best previous limit by 4 orders of magnitude.
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White CG, Burnstein RA, Chakravorty A, Chan A, Chen YC, Choong WS, Clark K, Dukes EC, Durandet C, Felix J, Gidal G, Gu P, Gustafson HR, Ho C, Holmstrom T, Huang M, James C, Jenkins CM, Kaplan DM, Lederman LM, Leros N, Longo MJ, Lopez F, Lu LC, Luebke W, Luk KB, Nelson KS, Park HK, Perroud JP, Rajaram D, Rubin HA, Teng PK, Volk J, White SL, Zyla P. Search for DeltaS = 2 nonleptonic hyperon decays. PHYSICAL REVIEW LETTERS 2005; 94:101804. [PMID: 15783474 DOI: 10.1103/physrevlett.94.101804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Indexed: 05/24/2023]
Abstract
A sensitive search for the rare decays Omega(-)--> Lambdapi(-) and Xi(0)--> ppi(-) has been performed using data from the 1997 run of the HyperCP (Fermilab E871) experiment. Limits on other such processes do not exclude the possibility of observable rates for |DeltaS| = 2 nonleptonic hyperon decays, provided the decays occur through parity-odd operators. We obtain the branching-fraction limits B(Omega(-)-->Lambdapi(-)) < 2.9 x 10(-6) and B(Xi(0)--> ppi(-)) < 8.2 x 10(-6), both at 90% confidence level.
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214
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Heng JB, Aksimentiev A, Ho C, Dimitrov V, Sorsch T, Miner J, Mansfield W, Schulten K, Timp G. Beyond the Gene Chip. BELL LABS TECHNICAL JOURNAL 2005; 10:5-22. [PMID: 18815623 PMCID: PMC2546600 DOI: 10.1002/bltj.20102] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We describe a prospective strategy for reading the encyclopedic information encoded in the genome: using a nanopore in a membrane formed from an MOS-capacitor to sense the charge in DNA. In principle, as DNA permeates the capacitor-membrane through the pore, the electrostatic charge distribution characteristic of the molecule should polarize the capacitor and induce a voltage on the electrodes that can be measured. Silicon nanofabrication and molecular dynamic simulations with atomic detail are technological linchpins in the development of this detector. The sub-nanometer precision available through silicon nanotechnology facilitates the fabrication of the detector, and molecular dynamics provides us with a means to design it and analyze the experimental outcomes.
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Holmstrom T, Leros N, Burnstein RA, Chakravorty A, Chan A, Chen YC, Choong WS, Clark K, Dukes EC, Durandet C, Felix J, Fu Y, Gidal G, Gu P, Gustafson HR, Ho C, Huang M, James C, Jenkins CM, Jones T, Kaplan DM, Lederman LM, Longo MJ, Lopez F, Lu LC, Luebke W, Luk KB, Nelson KS, Park HK, Perroud JP, Rajaram D, Rubin HA, Teng PK, Volk J, White CG, White SL, Zyla P. Search for CP violation in charged-Xi and Lambda hyperon decays. PHYSICAL REVIEW LETTERS 2004; 93:262001. [PMID: 15697968 DOI: 10.1103/physrevlett.93.262001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Indexed: 05/24/2023]
Abstract
We have compared the p and p angular distributions in 117 x 10(6) Xi- -->Lambdapi- -->ppi-pi- and 41 x 10(6) Xi+ -->Lambda pi+ -->p pi+pi+ decays using a subset of the data from the HyperCP experiment (E871) at Fermilab. We find no evidence of CP violation, with the direct-CP-violating parameter AXiLambda identical with (alphaXialphaLambda-alpha Xialpha Lambda)/(alphaXialphaLambda+alphaXialphaLambda)=[0.0+/-5.1(stat)+/-4.4(syst)] x 10(-4).
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Farmer M, Edward L, Westcott C, Mishra G, Melin S, Ho C, Blackstock A. Pre-operative hyperfractionated radiotherapy and concurrent 5-fu/cisplatin for locally advanced esophageal cancer - the impact of 18-F-fluoro-deoxy-d-glucose (FDG) positron emission tomography staging. Int J Radiat Oncol Biol Phys 2004. [DOI: 10.1016/j.ijrobp.2004.07.302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ho C, Murray N, Melosky B, Laskin J, Anderson H, Karim RR, Hamata L, Bebb G. The BC Cancer Agency experience with gefitinib in advanced non-small cell lung cancer (NSCLC). J Clin Oncol 2004. [DOI: 10.1200/jco.2004.22.90140.3104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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218
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Cheung BMY, Ho C, Kou KO, Kuong EEYL, Lai KW, Leow PL, Tam PK, Tse KS, Tung KL, Woo PYM. Knowledge of cardiopulmonary resuscitation among the public in Hong Kong: telephone questionnaire survey. Hong Kong Med J 2003; 9:323-8. [PMID: 14530525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
OBJECTIVES To evaluate the knowledge of basic life-support and training experience in cardiopulmonary resuscitation among the public in Hong Kong and to identify areas for improvement in public education. DESIGN Telephone interview using a structured multiple-choice questionnaire. SETTING Random cross-section of the Hong Kong public, from mid-March to May 2002. PARTICIPANTS Men and women aged 16 years and older selected using random telephone dialling. MAIN OUTCOME MEASURE Overall score in the cardiopulmonary resuscitation knowledge questionnaire. RESULTS Of the 357 participants, approximately 12% had received cardiopulmonary resuscitation training. Cardiopulmonary resuscitation knowledge in Hong Kong was poor, even among the previously trained and especially with regard to circulatory maintenance. The most common reason for not taking cardiopulmonary resuscitation training was lack of time. CONCLUSION The degree of citizen preparedness in initiating cardiopulmonary resuscitation is very poor in Hong Kong. Intensified educational efforts and exploration of new approaches to improve this first stage in the chain of survival are warranted.
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Hodges L, Lacayo C, Chinn L, Ho C, Lillehammer T, Pauli-Magnus C, Kroetz D. Ala893ser variant has no effect on p-glycoprotein (P-GP) function. Clin Pharmacol Ther 2003. [DOI: 10.1016/s0009-9236(03)90404-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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220
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Ho C, McCouch R, Smith E. Improvement of hybrid yield by advanced backcross QTL analysis in elite maize. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2002; 105:440-448. [PMID: 12582549 DOI: 10.1007/s00122-002-0945-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2001] [Accepted: 11/14/2001] [Indexed: 05/17/2023]
Abstract
We applied an advanced backcross breeding strategy to identify quantitative trait loci (QTLs) of agronomic importance in a cross between two elite inbreds of maize, RD6502 (Mo17-type recurrent parent) and RD3013 (Iodent donor parent). Two hundred and four BC(2) families were scored at 106 SSR, 15 AFLP, and 38 Heartbreaker (MITE) loci. BC(2) testcrosses (TC) with B73 were phenotyped at six locations in the Midwest and N.Y. We detected four grain yield, six grain moisture, and three plant height QTLs at which the RD3013 allele had a favorable effect ( p < 0.05). All four yield QTLs were selected as target introgressions in the development of BC(3)TC families. As predicted by BC(2)TC analysis, BC(3)TC entries containing introgressions at yld3.1 and yld10.1 significantly outperformed non-carrier entries by 11.1% (15.6 bu/A at one location) and 6.7% (7.1 bu/A averaged across two locations), respectively, in replicated Midwestern trials ( p < 0.05). Detection of yld10.1 effects in the BC(2)TC by spatial analysis (i.e., incomplete block, response surface, autoregressive, moving average or autoregressive moving average), but not by conventional single point analysis or interval mapping, indicated the utility of local environmental control for QTL mapping in unreplicated maize progeny. This work demonstrated that the advanced backcross QTL method can be applied to identify and manipulate useful QTLs in heterotic inbreds of elite maize. Genetic gains by this approach can be coupled with the maintenance and selection of favorable epistatic gene complexes by traditional hybrid breeding for maize improvement.
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Park HK, Burnstein RA, Chakravorty A, Chan A, Chen YC, Choong WS, Clark K, Dukes EC, Durandet C, Felix J, Gidal G, Gu P, Gustafson HR, Ho C, Holmstrom T, Huang M, James C, Jenkins CM, Kaplan DM, Lederman LM, Leros N, Longo MJ, Lopez F, Lu L, Luebke W, Luk KB, Nelson KS, Perroud JP, Rajaram D, Rubin HA, Teng PK, Volk J, White C, White S, Zyla P. Observation of the decay K- --> pi(-)mu(+)mu(-) and measurements of the branching ratios for K+/- --> pi(+/-)mu(+)mu(-). PHYSICAL REVIEW LETTERS 2002; 88:111801. [PMID: 11909394 DOI: 10.1103/physrevlett.88.111801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2001] [Indexed: 05/23/2023]
Abstract
Using data collected with the HyperCP (E871) spectrometer during the 1997 fixed-target run at Fermilab, we report the first observation of the decay K--->pi(-)mu(+)mu(-) and new measurements of the branching ratios for K+/--->pi(+/-)mu(+)mu(-). By combining the branching ratios for the decays K+-->pi(+)mu(+)mu(-) and K--->pi(-)mu(+)mu(-), we measure Gamma(K+/--->pi(+/-)mu(+)mu(-))/Gamma(K+/--->all) = (9.8+/-1.0+/-0.5)x10(-8). The CP asymmetry between the rates of the two decay modes is [Gamma(K+-->pi(+)mu(+)mu(-))-Gamma(K--->pi(-)mu(+)mu(-))]/[Gamma(K+-->pi(+)mu(+)mu(-))+Gamma(K--->pi(-)mu(+)mu(-))] = -0.02+/-0.11+/-0.04.
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Yang D, Ye Q, Williams M, Sun Y, Hu TC, Williams DS, Moura JM, Ho C. USPIO-enhanced dynamic MRI: evaluation of normal and transplanted rat kidneys. Magn Reson Med 2001; 46:1152-63. [PMID: 11746582 DOI: 10.1002/mrm.1312] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To evaluate first-pass renal perfusion with ultrasmall superparamagnetic iron oxide (USPIO) particles by MRI, 40 normal rats (20 Dark Agouti (DA) rats and 20 Brown Norway (BN) rats) and 16 transplanted rats (12 allografts and four isografts) were studied on day 4 post-transplantation with different USPIO doses (3.0-18.1 mg Fe/kg/body weight). All animals underwent 128 consecutive snapshot fast low-angle shot (FLASH) coronal dynamic studies in 43 s. In the normal rats, a larger maximum signal decrease (MSD) in the cortex and the outer medulla is observed with an increasing dose of USPIO particles (P < 0.01). No significant differences were observed between the right and left kidneys at all doses studied. Higher MSD, time of occurrence of MSD (tMSD), and wash-in slope appear with higher doses of USPIO particles. The dynamic curves for DA rats show similar shapes when compared to those for BN rats. In the transplanted rats, allograft kidneys show lower MSD, longer tMSD, and lower wash-in slope compared to those in the normal kidneys. Isograft kidneys show perfusion patterns similar to those of normal kidneys in the cortex and the outer medulla. Histopathology indicates acute vascular rejection in all allografts and normal kidney architecture in all isografts. The results clearly show good agreement between the renal graft perfusion measurements and histopathological changes associated with rejection. This work also introduces a new signal analysis methodology for the automatic detection of transplanted organ rejection. This method compares the dynamics of the intrarenal signal intensities for native and transplanted kidneys. A quantitative measurement to detect significant differences between these signals was developed, and showed that this technique exhibits good performance in identifying renal rejection.
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Tsai CH, Larson SC, Shen TJ, Ho NT, Fisher GW, Tam MF, Ho C. Probing the importance of the amino-terminal sequence of the beta- and gamma-chains to the properties of normal adult and fetal hemoglobins. Biochemistry 2001; 40:12169-77. [PMID: 11580292 DOI: 10.1021/bi0111045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A recombinant mutant of human fetal hemoglobin (Hb F), named rHb Oscar, has been constructed to explore the importance of the sequence of the amino-terminal region of the gamma-chain to the structural and functional properties of Hb F as compared to human normal adult hemoglobin (Hb A). Substitutions in the N-terminal region of Hb A have shown this region to be important to its structural and functional properties. Recent studies of recombinant mutants of Hb A with gamma-chain mutations have been used to probe the significance of the N-terminal sequence to the properties of Hb F. One of these mutants of Hb A, called rHb Felix, contains eight substitutions in the N-terminal region of the beta-chain corresponding to the sequence of the gamma-chain in that region [Dumoulin et al. (1998) J. Biol. Chem. 273, 35032-35038]. rHb Felix exhibits a 2,3-bisphosphoglycerate (2,3-BPG) response like that of Hb A, but its tetramer-dimer dissociation constant is similar to that of Hb F. In contrast, rHb Oscar contains a gamma-chain with eight mutations at the N-terminal end corresponding to the sequence of the beta-chain of Hb A in that region. (1)H NMR studies of rHb Oscar indicate a global structure like that of Hb F. rHb Oscar is not as stable against alkaline denaturation as Hb F but is more stable than Hb A, and it exhibits a stronger response to 2,3-BPG and inositol hexaphosphate as compared to Hb F. The 2,3-BPG effect in rHb Oscar also appears to be slightly enhanced compared to that in Hb A. Subzero isoelectric focusing experiments suggest that rHb Oscar does not have dissociation properties like those of Hb A. These results along with those of rHb Felix illustrate that the effects of the N-terminal region on structure and function of the Hb molecule are complicated by interactions with the rest of the molecule that are not yet well defined. However, studies of complementary mutations of Hb A and Hb F may eventually help to define such interactions and lead to a better understanding of the relationship between the amino acid sequence and the properties of the Hb molecule.
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Ho C. Transdermally-delivered oxybutynin (Oxytrol(R) for overactive bladder. ISSUES IN EMERGING HEALTH TECHNOLOGIES 2001:1-4. [PMID: 11776281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
(1) The oxybutynin patch is a transdermal delivery system, which releases the drug oxybutynin through the skin for the management of overactive bladder. (2) Limited evidence suggests that transdermal delivery of oxybutynin over a short period of time may have efficacy comparable to oral oxybutynin. (3) Recent phase II and III clinical trials supported by the manufacturer suggest a potentially reduced incidence of dry mouth compared to oral oxybutynin. Itching, however, is present in 18% of patients, and the patients' withdrawal rate due to adverse events after 12 weeks is significant (10%). (4) More studies are required to determine the long-term efficacy and safety of the oxybutynin patch for overactive bladder. (5) A New Drug Application for transdermal oxybutynin (Oxytrol(R)) is currently under review at the U.S. Food and Drug Administration. As of October 2001, the oxybutynin patch has not been approved in Canada.
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Ho C, Slater SJ, Stagliano B, Stubbs CD. The C1 domain of protein kinase C as a lipid bilayer surface sensing module. Biochemistry 2001; 40:10334-41. [PMID: 11513612 DOI: 10.1021/bi002839x] [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: 11/28/2022]
Abstract
The activity of membrane-associated protein kinase C (PKC) is tightly controlled by the physical properties of the membrane lipid bilayer, in particular, curvature stress, which is induced by bilayer-destabilizing lipid components. An important example of this is the weakened lipid headgroup interactions induced by phosphatidylethanolamine (PE) and cholesterol. In this work our previous observation with a mixed isoform PKC showing a biphasic dependence of activity as a function of membrane curvature stress [Slater et al. (1994) J. Biol. Chem. 269, 4866-4871] was here extended to individual isoforms. The Ca(2+)-dependent PKCalpha, PKCbeta, and PKCgamma, along with Ca(2+)-independent PKCdelta, but not PKCepsilon or PKCzeta, displayed a biphasic activity as a function of membrane PE content. The fluorescence anisotropy of N-(5-dimethylaminonaphthalene-1-sulfonyl)dioleoylphosphatidylserine (dansyl-PS), which probes the lipid environment of PKC, also followed a biphasic profile as a function of PE content for full-length PKCalpha, PKCbetaIotaIota, and PKCgamma as did the isolated C1 domain of PKCalpha. In addition, the rotational correlation time of both PKCalpha and PKCdelta C1-domain-associated sapintoxin D, a fluorescent phorbol ester, was also a biphasic function of membrane lipid PE content. These results indicate that the C1 domain acts as a sensor of the bilayer surface properties and that its conformational response to these effects may directly underlie the resultant effects on enzyme activity.
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Kanno S, Wu YJ, Lee PC, Dodd SJ, Williams M, Griffith BP, Ho C. Macrophage accumulation associated with rat cardiac allograft rejection detected by magnetic resonance imaging with ultrasmall superparamagnetic iron oxide particles. Circulation 2001; 104:934-8. [PMID: 11514382 DOI: 10.1161/hc3401.093148] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Acute cardiac allograft rejection continues to be the cause of graft loss and contributes to the morbidity and mortality after cardiac transplantation. In this study, we report a new method for detecting organ rejection in transplantation with an MR-based technique using dextran-coated ultrasmall superparamagnetic iron oxide (USPIO) particles. These particles ( approximately 27 nm in diameter) are known to shorten relaxation times in MRI experiments. METHODS AND RESULTS A new rat model of heterotopic heart and lung transplantation has been developed for MRI experiments. Allotransplantations (DA-->BN) were performed (n=8), with syngeneic transplantations (BN-->BN) serving as controls (n=8). MR images were obtained with a gradient echo method. At postoperative day 7, allotransplants developed moderate rejection as determined histopathologically. A significant reduction in MR signal intensity was observed after USPIO injection into rats with allotransplanted hearts. Syngeneic transplants showed no differences in MR signal intensity before and after USPIO injections. After injection of USPIO particles at postoperative day 6, a group of allotransplanted rats was treated with cyclosporin A (3 mg/kg). Animals treated with cyclosporin A for 7 days showed no reduction in MR signal intensity after USPIO reinjection at day 14, whereas animals treated for 4 days showed a significant decrease in MR signal intensity in the transplanted hearts indicative of acute graft rejection. Pathological analysis of these animals revealed that dextran-coated USPIO particles were taken up by the infiltrating macrophages that accumulated within the rejecting cardiac graft. CONCLUSIONS This MRI method offers promise as a noninvasive method for detecting transplant allograft rejection.
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Kanno S, Wu YJ, Lee PC, Billiar TR, Ho C. Angiotensin-converting enzyme inhibitor preserves p21 and endothelial nitric oxide synthase expression in monocrotaline-induced pulmonary arterial hypertension in rats. Circulation 2001; 104:945-50. [PMID: 11514384 DOI: 10.1161/hc3401.093155] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pulmonary arterial hypertension (PAH) is associated with structural changes in the pulmonary vasculature characterized by the proliferation of cellular components of the vessels. ACE inhibitor (ACEI) may have beneficial effects in treating PAH, but its precise mechanism of action in the remodeling process is unclear. p21 is a cyclin-dependent kinase inhibitor that may have a protective role in this process by inhibiting cellular proliferation. Endothelial nitric oxide synthase (eNOS) has also been shown to be protective by its vasodilatory effect. Therefore, we investigated whether expression of p21 and eNOS was modulated by ACEI treatment in a rat model. METHODS AND RESULTS Monocrotaline (MCT) was administered to 2 groups of Sprague-Dawley rats fed a high-cholesterol diet, ie, one group received MCT concomitantly with enalapril treatment (MCT(+)/ACEI(+) rats), and the other group did not receive enalapril (MCT(+)/ACEI(-) rats). After 5 weeks, MRI showed right ventricular hypertrophy in MCT(+)/ACEI(-) rats. MCT(+)/ACEI(+) rats showed a preserved right ventricular morphology. Isolated pulmonary perfusion studies showed that ACEI significantly upregulated NO production, as measured by nitrite levels. Addition of N-methyl-D-glucamine dithiocarbamate-Fe solution, an NO-trapping agent, reversed the basal vasodilatory effect of ACEI in the pulmonary vasculature. Immunoblot analysis showed decreased p21 and eNOS expression in the lung in MCT(+)/ACEI(-) rats, whereas their expression was preserved with enalapril treatment. CONCLUSIONS ACEI suppresses the development of MCT-induced PAH in rats. The mechanism of action might involve the preservation of p21 and eNOS expression. Both p21 and endothelium-derived NO appear to have protective roles in the development of PAH.
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MESH Headings
- Angiotensin-Converting Enzyme Inhibitors/pharmacology
- Animals
- Blood Pressure/drug effects
- Cells, Cultured
- Cyclin-Dependent Kinase Inhibitor p21
- Cyclins/metabolism
- Dietary Fats
- Disease Models, Animal
- Enalapril/pharmacology
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/complications
- Hypertension, Pulmonary/drug therapy
- Hypertension, Pulmonary/physiopathology
- Hypertrophy, Right Ventricular/diagnosis
- Hypertrophy, Right Ventricular/etiology
- Hypertrophy, Right Ventricular/physiopathology
- In Vitro Techniques
- Lung/blood supply
- Lung/drug effects
- Lung/metabolism
- Lung/pathology
- Magnetic Resonance Imaging
- Male
- Monocrotaline
- Nitrates/metabolism
- Nitric Oxide Donors/pharmacology
- Nitric Oxide Synthase/biosynthesis
- Nitric Oxide Synthase Type III
- Nitrites/metabolism
- Perfusion
- Pulmonary Artery/drug effects
- Pulmonary Artery/pathology
- Pulmonary Artery/physiopathology
- Rats
- Rats, Sprague-Dawley
- Signal Transduction/drug effects
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Slater SJ, Seiz JL, Stagliano BA, Cook AC, Milano SK, Ho C, Stubbs CD. Low- and high-affinity phorbol ester and diglyceride interactions with protein kinase C: 1-O-alkyl-2-acyl-sn-glycerol enhances phorbol ester- and diacylglycerol-induced activity but alone does not induce activity. Biochemistry 2001; 40:6085-92. [PMID: 11352745 DOI: 10.1021/bi001002z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phorbol ester-induced conventional protein kinase C (PKCalpha, -betaIota/IotaIota, and -gamma) isozyme activities are potentiated by 1,2-diacyl-sn-glycerol. This has been attributed to a "cooperative" interaction of the two activators with two discrete sites termed the low- and high-affinity phorbol ester binding sites, respectively [Slater, S. J., Milano, S. K., Stagliano, B. A., Gergich, K. J., Ho, C., Mazurek, A., Taddeo, F. J., Kelly, M. B., Yeager, M. D., and Stubbs, C. D. (1999) Biochemistry 38, 3804-3815]. Here, we report that the 1-O-alkyl ether diglyceride, 1-O-hexadecyl-2-acetyl-sn-glycerol (HAG), like its 1,2-diacyl counterpart, 1-oleoyl-2-acetyl-sn-glycerol (OAG), also potentiated PKCalpha, -betaI/II, and -gamma activities induced by the phorbol ester 4beta-12-O-tetradecanoylphorbol-13-acetate (TPA). Similar to OAG, HAG was found to bind to the low-affinity phorbol ester binding site and to enhance high-affinity phorbol ester binding, and to decrease the level of Ca(2+) required for phorbol ester-induced activity, while being without effect on the Ca(2+) dependence of membrane association. Thus, similar to OAG, HAG may also potentiate phorbol ester-induced activity by interacting with the low-affinity phorbol ester binding site, leading to a reduced level of Ca(2+) required for the activating conformational change. However, HAG was found not to behave like a 1,2-diacyl-sn-glycerol in that alone it did not induce PKC activity, and also in that it enhanced OAG-induced activity. The results reveal HAG to be a member of a new class of "nonactivating" compounds that modulate PKC activity by interacting with the low-affinity phorbol ester binding site.
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Abstract
A tumor that affects the central nervous system can have a dramatic impact on the individual affected, as well as his or her family and friends. The tumor, regardless of extent or location, may affect the physical, social, vocational, and emotional capabilities of the individual. Basic aspects of rehabilitation for patients with tumors affecting the brain and spinal cord are reviewed in this article. The authors have found that the same principles of neurorehabilitation applied to persons with traumatic brain injury, stroke, and traumatic spinal cord injury are equally appropriate for persons with brain and spinal cord tumors. These principles include the prevention of medical complications; the treatment of medical problems such as pain, spasticity, and neuropathic bowel and bladder; and the improvement of patients' mobility and activities of daily living. Rehabilitation specialists can help prevent complications, maximize function, and improve the quality of life for patients with central nervous system tumors.
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Robertson CL, Hendrich KS, Kochanek PM, Jackson EK, Melick JA, Graham SH, Marion DW, Williams DS, Ho C. Assessment of 2-chloroadenosine treatment after experimental traumatic brain injury in the rat using arterial spin-labeled MRI: a preliminary report. ACTA NEUROCHIRURGICA. SUPPLEMENT 2001; 76:187-9. [PMID: 11450003 DOI: 10.1007/978-3-7091-6346-7_37] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Adenosine is a putative endogenous neuroprotectant. Its action at A1 receptors mitigates excitotoxicity while action at A2 receptors increases cerebral blood flow (CBF). We hypothesized that cerebral injection of the adenosine analog, 2-chloroadenosine, would decrease swelling and increase CBF early after experimental traumatic brain injury (TBI). To test this hypothesis, rats were anesthetized and subjected to TBI using a controlled cortical impact (CCI) model (n = 5/group). Immediately after injury, 2-chloroadenosine (0.3 nmole in 2 microliters) or an equal volume of vehicle were stereotactically injected lateral to the area of contusion. Using magnetic resonance imaging (MRI), in vivo spin-lattice relaxation time of tissue water (Tlobs) and CBF (arterial spin labeling) were measured in a 2-mm thick slice in the injured and non-injured hemispheres at 3-4 h after CCI. In a separate, preliminary experiment, the effect of 2-chloroadenosine injection in normal rat brain was studied. Rats (n = 2) were anesthetized and a burr hole was made for injection of 2-chloroadenosine into the same site as in the TBI model. One rat received the standard dose of 0.3 nmole and one rat received a 6 nmole injection. Tlobs and CBF studies were obtained 1.5-3.5 h after injection, using the same MRI methods as in the TBI study. In rats subjected to TBI, treatment with 2-chloroadenosine attenuated the increase in Tlobs after injury (p < 0.05 for treatment vs vehicle) in both hippocampus and cortex ipsilateral to injury. However, treatment with 2-chloroadenosine did not improve post-traumatic hypoperfusion. In normal rats, injection of 0.3 nmole of 2-chloroadenosine did not increase CBF, but the higher dosage of 6 nmole dramatically increased hemispheric CBF by 1.5-2.0-fold. The effect of local injection of 2-chloroadenosine at a dose of 0.3 nmole after experimental TBI on Tlobs presumably represents a reduction in post-traumatic edema. This reduction in edema, along with the augmentation of CBF seen in normal rats at higher dosage (6 nmole), supports a role for adenosine in neuroprotection following TBI.
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Abstract
The popularity and use of unmotorized, foot-propelled scooters has risen dramatically in the last few years. Increasing reports of traumatic injuries from these scooters have paralleled their commercial sales and success in this country and worldwide. We report a case of a previously healthy 48-year-old woman who suffered a severe traumatic brain injury while riding one of these scooters, resulting in a devastating neurologic outcome and permanent vegetative state. This case emphasizes the importance of public awareness regarding the potential dangers and the need for appropriate precautions and protective gear when riding these recreational devices.
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232
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Hirst M, Ho C, Sabourin L, Rudnicki M, Penn L, Sadowski I. A two-hybrid system for transactivator bait proteins. Proc Natl Acad Sci U S A 2001; 98:8726-31. [PMID: 11447261 PMCID: PMC37503 DOI: 10.1073/pnas.141413598] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We describe a two-hybrid strategy for detection of interactions with transactivator proteins. This repressed transactivator (RTA) system employs the N-terminal repression domain of the yeast general repressor TUP1. TUP1-GAL80 fusion proteins, when coexpressed with GAL4, are shown to inhibit transcription of GAL4-dependent reporter genes. This effect requires the C-terminal 30 residues of GAL4, which are required for interaction with GAL80 in vitro. Furthermore, repression of GAL transcription by TUP1-GAL80 requires SRB10, demonstrating that the TUP1 repression domain, in the context of a two-hybrid interaction, functions by the same mechanism as endogenous TUP1. Using this strategy, we demonstrate interactions between the mammalian basic helix-loop-helix proteins MyoD and E12, and between c-Myc and Bin-1. We have also identified interacting clones from a TUP1-cDNA fusion expression library by using GAL4-VP16 as a bait fusion. These results demonstrate that RTA is generally applicable for identifying and characterizing interactions with transactivator proteins in vivo.
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Hendrich KS, Kochanek PM, Melick JA, Schiding JK, Statler KD, Williams DS, Marion DW, Ho C. Cerebral perfusion during anesthesia with fentanyl, isoflurane, or pentobarbital in normal rats studied by arterial spin-labeled MRI. Magn Reson Med 2001; 46:202-6. [PMID: 11443729 DOI: 10.1002/mrm.1178] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The influence of anesthetic agents on cerebral blood flow (CBF) was tested in normal rats. CBF is quantified with arterial spin-labeled MRI in rats anesthetized with either an opiate (fentanyl), a potent inhalation anesthetic agent (isoflurane), or a barbiturate (pentobarbital) using doses commonly employed in experimental paradigms. CBF values were found to be about 2.5-3 times lower in most regions analyzed during anesthesia with either fentanyl (with N(2)O/O(2)) or pentobarbital vs. isoflurane (with N(2)O/O(2)), in agreement with findings utilizing invasive measurement techniques. CBF was heterogeneous in rats anesthetized with isoflurane (with N(2)O/O(2)), but relatively homogeneous in rats anesthetized with either fentanyl (with N(2)O/O(2)) or pentobarbital, also in agreement with studies using other techniques. Magn Reson Med 46:202-206, 2001.
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Ho C. Rosuvastatin: do we need another statin? ISSUES IN EMERGING HEALTH TECHNOLOGIES 2001:1-4. [PMID: 11776286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
(1) Rosuvastatin (Crestor(TM)) is a new synthetic agent for the treatment and prevention of lipid disorders, a risk factor for coronary heart disease. (2) Rosuvastatin is undergoing phase III clinical trials. A New Drug Application was submitted to the U.S. Food and Drug Administration in June, 2001. No information on the regulatory status in Canada is currently available. (3) Limited evidence from small clinical trials suggests that rosuvastatin may produce larger dose-dependent decreases in total cholesterol levels and low-density lipoprotein-cholesterol levels in hypercholesterolemic patients compared to other statins. There is insufficient evidence to draw conclusions about the safety of rosuvastatin. (4) The impact of rosuvastatin therapy on cardiac morbidity and mortality is not known. More experience is required to determine the effectiveness and relative benefits of this new drug.
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235
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Lin JD, Chen JF, Chang HY, Ho C. Evaluation of bone mineral density by quantitative ultrasound of bone in 16,862 subjects during routine health examination. Br J Radiol 2001; 74:602-6. [PMID: 11509395 DOI: 10.1259/bjr.74.883.740602] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Caucasians and Asians are among those with the highest risk for involutional osteoporosis. To obtain accurate data about the prevalence of osteoporosis or osteopenia in different age groups, a large epidemiological study is necessary. Quantitative ultrasound (QUS) of bone is a promising technique in assessing bone microarchitecture in addition to bone mass. This study had two aims. The first was to establish bone mineral density (BMD) using QUS in subjects with no obvious disease undergoing routine health examination. The second was to determine risk factors for osteoporosis in Taiwan in order that better prevention and treatment measures may be provided for these patients. A prospective study of the risk factors for fracture was conducted in the health examination division of Chang Gung Medical Center in Linkou, Taiwan, from January 1996 to December 1997. Broadband ultrasound attenuation of the right heel was measured with an achilles bone densitometer (Lunar, Nauheim, Germany). A total of 16,862 subjects were examined, including 9,314 women (mean age 51.5+/-11.7 years) and 7,548 men (mean age 51.1+/-12.1 years). The incidence of osteoporosis in all subjects increased from 1.13% in the 21--30-year-old age group to 54.55% in those over 80 years of age. 12.02% of the subjects had osteoporosis and 34.45% had osteopenia. From multivariate analysis, bone density evaluated by QUS showed a relationship with age, gender, body mass index, waist/hip ratio, smoking and frequency of exercise. In conclusion, BMD evaluated by QUS is not found to be higher in Taiwan than elsewhere. The role of QUS in predicting fractures in Taiwan requires further investigation.
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Khatri IA, Ho C, Specian RD, Forstner JF. Characteristics of rodent intestinal mucin Muc3 and alterations in a mouse model of human cystic fibrosis. Am J Physiol Gastrointest Liver Physiol 2001; 280:G1321-30. [PMID: 11352827 DOI: 10.1152/ajpgi.2001.280.6.g1321] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Human mucin MUC3 and rodent Muc3 are widely assumed to represent secretory mucins expressed in columnar and goblet cells of the intestine. Using a 3'-oligonucleotide probe and in situ hybridization, we observed expression of rat Muc3 mostly in columnar cells. Two antibodies specific for COOH-terminal epitopes of Muc3 localized to apical membranes and cytoplasm of columnar cells. An antibody to the tandem repeat (TR) sequence (TTTPDV)3, however, localized to both columnar and goblet cells. On CsCl gradients, Muc3 appeared in both light- and heavy-density fractions. The lighter species was immunoreactive with all three antibodies, whereas the heavier species reacted only with anti-TR antibody. Thus Muc3 is expressed in two forms, a full-length membrane-associated form found in columnar cells (light density) and a carboxyl-truncated soluble form present in goblet cells (heavy density). In a mouse model of human cystic fibrosis, both soluble Muc3 and goblet cell Muc2 were increased in amount and hypersecreted. Thus Muc2 and Muc3 contribute to the excess intestinal luminal mucus of cystic fibrosis mice.
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Ho C, Shumack SP, Morris D. Subacute cutaneous lupus erythematosus associated with hepatocellular carcinoma. Australas J Dermatol 2001; 42:110-3. [PMID: 11309033 DOI: 10.1046/j.1440-0960.2001.00491.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A 63-year-old man with a 4-year history of metastatic hepatocellular carcinoma secondary to chronic hepatitis B developed a rash affecting his arms, legs, thorax and back. Both clinical and histological examination suggested a diagnosis of subacute cutaneous lupus erythematosus (SCLE). The association of SCLE and hepatocellular carcinoma has not previously been reported. The SCLE persisted without remission and was still present at his death from metastatic hepatocellular carcinoma 3 months later. We also review other reported cases of SCLE as paraneoplastic dermatoses and apply McLean's criteria for paraneoplastic dermatosis.
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Kochanek PM, Hendrich KS, Robertson CL, Williams DS, Melick JA, Ho C, Marion DW, Jackson EK. Assessment of the effect of 2-chloroadenosine in normal rat brain using spin-labeled MRI measurement of perfusion. Magn Reson Med 2001; 45:924-9. [PMID: 11323821 DOI: 10.1002/mrm.1123] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adenosine analogs such as 2-chloroadenosine are potent cerebrovasodilators. Spin-labeled MRI was used to investigate the spatial distribution, dose-response, and timing of the effect of 2-chloroadenosine on cerebral blood flow (CBF) after intraparenchymal injection into rat brain. Sprague-Dawley rats (N = 10) were injected with 2-chloroadenosine at doses of 0.3, 6.0, or 12 nmoles, or saline vehicle (2-4 microL). CBF was serially quantified in a slice through the injection site in a circular (3.6 mm diameter) region of interest (ROI) around the injection and in ipsilateral hemispheric ROIs at approximately 90 min and approximately 180 min. Marked 3.77- and 3.93-fold increases in CBF (vs. vehicle) were seen in the circular ROI at approximately 90 min and approximately 180 min after 12-nmol injection, respectively. Similarly, 2.92- and 2.78-fold increases in hemispheric CBF were observed at approximately 90 min and approximately 180 min, respectively, after injection of 12 nmoles. Linear dose-response relationships were observed at both times after injection in both ROIs (all P < 0.01). Spin-labeling MRI assessment revealed that parenchymal injection of 2-chloroadenosine produces potent, dose-dependent, and sustained vasodilation over large areas of brain. This treatment and imaging paradigm should facilitate investigation of the effect of CBF promotion in models of traumatic and ischemic brain injury.
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Barrick D, Ho NT, Simplaceanu V, Ho C. Distal ligand reactivity and quaternary structure studies of proximally detached hemoglobins. Biochemistry 2001; 40:3780-95. [PMID: 11300758 DOI: 10.1021/bi002165q] [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: 11/29/2022]
Abstract
The linkage between the proximal histidines and the proximal polypeptide in normal adult human hemoglobin (Hb A) has been proposed to play a major role in transmitting allosteric effects between oxygen binding sites [Perutz, M. F. (1970) Nature 228, 726-734]. Here we present circular dichroism (CD), (1)H NMR, analytical ultracentrifugation, and stopped-flow kinetic data to better define the quaternary structure of hemoglobins in which the linkage between the proximal histidines and the polypeptide backbone has been broken [Barrick et al. Nat. Struct. Biol. 4, 78-83 (1997)] and to characterize the distal ligand binding properties of these proximally detached Hbs. CD spectroscopy indicates that rHb (alphaH87G) and rHb (alphaH87G/betaH92G) retain at least partial T-quaternary structure with distal ligand bound, whereas rHb (betaH92G) does not, consistent with (1)H NMR spectra. Analytical ultracentrifugation reveals significant tetramer dissociation in rHb (betaH92G) to be the likely cause of loss of T-state markers. These quaternary structure studies indicate that in distally liganded Hb, the T-state is compatible with proximal linkages in the beta- but not the alpha-chains. (1)H NMR titrations of rHb (alphaH87G) with n-butyl isocyanide demonstrate the alpha-chains to be of high affinity as compared with the beta-chains. Comparing ligand association and dissociation rates between the rHb (alphaH87G) variant with the T- and R-states of wild-type Hb A indicates that at the alpha-chains, carbon monoxide affinity is modulated entirely by the proximal linkage, rather than from distal interactions. Some residual allosteric interactions may remain operative at the beta-chains of rHb (alphaH87G).
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241
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Ho C, Kurtzman SB. Three perspectives of cardiac electrical activity. BIOMEDICAL SCIENCES INSTRUMENTATION 2001; 37:325-30. [PMID: 11347411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
This article discusses three different perspectives of the electrical activity of the human heart based on three types of electrocardiographic recordings: the Surface ECG, the Subcutaneous ECG, and the Intracardiac Electrogram. Although all three types of recordings are generated by the same electrical activity, namely, the depolarization and repolarization of cardiac cells, the recordings have similarities and differences with regard to method of deployment, duration of implant, duration of recording, maximum long-term storage capacity, signal strength, and susceptibility to electrical noise. The article discusses the similarities and differences among the three types of recordings, as well as the engineering and clinical consequences of these similarities and differences. However, as the consequences include both advantages and disadvantages, the choice of any particular type of recording is eventually dependent on the user.
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Liu Y, Su B, Pei R, Yeh C, Yeh K, Ying Lee K, Hsu Y, Ho C, Lai Y. The stability of cytokeratin 18 in human liver cells during colchicine-induced microtubule disruption. Food Chem Toxicol 2001; 39:85-9. [PMID: 11259854 DOI: 10.1016/s0278-6915(00)00113-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cytoskeleton plays important roles in cell function and is therefore implicated in the pathogenesis of many human liver diseases, including malignant tumors. The stability of cytokeratin proteins during tumor transformation in human hepatocellular carcinoma has been studied with a molecular approach previously. The results demonstrate that the cytokeratin is modulated in human hepatocellular carcinoma. Besides this, three low molecular weight cytokeratin molecules (named HCC CK) are found. This indicates that these HCC CKs have undergone modulation from the human hepatocyte cytokeratin 18. We also checked the cytokeratin profile of the human hepatoma cell line PLC/PRF/5 with the same methods to ensure the HCC CK molecules are produced by modulation but not protein degradation. The stability of cytokeratin molecules was studied by a different approach. The cytokeratin compositions of human liver cells (Chang cell line) were analysed under the effects of microtubule-disrupting drug (colchicine) by SDS-PAGE, Western blot, immunoprecipitation using a commercially available monoclonal anti-cytokeratin 18 antibody and immunofluorescent staining. Within 1 h of treatment, the microtubule began to collapse and the filamentous structure was shortening. The microtubule had almost collapsed and became fragmented to form a lattice-like network after 24 h of treatment. The cytokeratin was modulated after long-term (24 h) treatment of colchicine, and the molecular weight became 14 kD and the antigenicity was lost. The stability of cytokeratin molecules was related to the intact microtubule network, after disruption of the microtubule the cytokeratin would be modulated. The intact microtubule network was a stabilizing factor of cytokeratin 18 in human liver cells.
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Ho C. Analysis of water vapor content in a ventilator. BIOMEDICAL SCIENCES INSTRUMENTATION 2001; 37:125-9. [PMID: 11347374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
For medical reasons, a humidifier is sometimes used to add moisture and heat to the air supplied by a ventilator to a patient. However, for a fixed mass of water vapor inside a container, the relative humidity of the air inside the container actually goes down when the temperature of the air is increased, since the saturated vapor pressure of water increases with temperature. Hence, for a type of humidifier that is designed to add only a small amount of water vapor to the patient's air intake, the increase in water vapor due to the humidifier may be hard to substantiate. This article presents one method of verifying that the amount of water in the patient circuit has been increased by the humidifier when the air temperature is also increased. An example will be included to illustrate this method.
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Fang TY, Simplaceanu V, Tsai CH, Ho NT, Ho C. An additional H-bond in the alpha 1 beta 2 interface as the structural basis for the low oxygen affinity and high cooperativity of a novel recombinant hemoglobin (beta L105W). Biochemistry 2000; 39:13708-18. [PMID: 11076510 DOI: 10.1021/bi001115i] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Site-directed mutagenesis has been used to construct three recombinant mutant hemoglobins (rHbs), rHb(beta L105W), rHb(alpha D94A/betaL105W), and rHb(alpha D94A). rHb(beta L105W) is designed to form a new hydrogen bond from beta 105Trp to alpha 94Asp in the alpha(1)beta(2) subunit interface to lower the oxygen binding affinity by stabilizing the deoxy quaternary structure. We have found that rHb(beta L105W) does indeed possess a very low oxygen affinity and maintains normal cooperativity (P(50) = 28.2 mmHg, n(max) = 2.6 in 0.1 M sodium phosphate at pH 7.4) compared to those of Hb A (P(50) = 9.9 mmHg, n(max) = 3.2 at pH 7.4). rHb(alpha D94A/beta L105W) and rHb(alpha D94A) are expressed to provide evidence that rHb(betaL 105W) does form a new H-bond from beta 105Trp to alpha 94Asp in the alpha(1)beta(2) subunit interface of the deoxy quaternary structure. Our multinuclear, multidimensional nuclear magnetic resonance (NMR) studies on (15)N-labeled rHb(beta L105W) have identified the indole nitrogen-attached (1)H resonance of beta 105Trp for rHb(beta L105W). (1)H NMR studies on Hb A and mutant rHbs have been used to investigate the structural basis for the low O(2) affinity of rHb(beta L105W). Our NMR results provide evidence that rHb(beta L105W) forms a new H-bond from beta 105Trp to alpha 94Asp in the alpha(1)beta(2) subunit interface of the deoxy quaternary structure. The NMR results also show that these three rHbs can switch from the R quaternary structure to the T quaternary structure in their ligated state upon addition of an allosteric effector, inositol hexaphosphate. We propose that the low O(2) affinity of rHb(beta L105W) is due to the formation of a new H-bond between alpha 105Trp and alpha 94Asp in the deoxy quaternary structure.
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Tsai CH, Fang TY, Ho NT, Ho C. Novel recombinant hemoglobin, rHb (beta N108Q), with low oxygen affinity, high cooperativity, and stability against autoxidation. Biochemistry 2000; 39:13719-29. [PMID: 11076511 DOI: 10.1021/bi001116a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using our Escherichia coli expression system, we have constructed rHb (beta N108Q), a new recombinant hemoglobin (rHb), with the amino acid substitution located in the alpha(1)beta(1) subunit interface and in the central cavity of the Hb molecule. rHb (beta N108Q) exhibits low oxygen affinity, high cooperativity, enhanced Bohr effect, and slower rate of autoxidation of the heme iron atoms from the Fe(2+) to the Fe(3+) state than other low-oxygen-affinity rHbs developed in our laboratory, e.g., rHb (alpha V96W) and rHb (alpha V96W, beta N108K). It has been reported by Olson and co-workers [Carver et al. (1992) J. Biol. Chem. 267, 14443-14450; Brantley et al. (1993) J. Biol. Chem. 268, 6995-7010] that the substitution of phenylalanine for leucine at position 29 of myoglobin can inhibit autoxidation in myoglobin and at position 29 of the alpha-chain of hemoglobin can lower NO reaction in both the deoxy and the oxy forms of human normal adult hemoglobin. Hence, we have further introduced this mutation, alpha L29F, into beta N108Q. rHb (alpha L29F, beta N108Q) is stabilized against auto- and NO-induced oxidation as compared to rHb (beta N108Q), but exhibits lower oxygen affinity at pH below 7.4 and good cooperativity as compared to Hb A. Proton nuclear magnetic resonance (NMR) studies show that rHb (beta N108Q) has similar tertiary structure around the heme pockets and quaternary structure in the alpha(1)beta(1) and alpha(1)beta(2) subunit interfaces as compared to those of Hb A. The tertiary structure of rHb (alpha L29F, beta N108Q) as measured by (1)H NMR, especially the alpha-chain heme pocket region (both proximal and distal histidyl residues), is different from that of CO- and deoxy-Hb A, due to the amino acid substitution at alpha L29F. (1)H NMR studies also demonstrate that rHb (beta N108Q) can switch from the R quaternary structure to the T quaternary structure without changing ligation state upon adding an allosteric effector, inositol hexaphosphate, and reducing the temperature. On the basis of its low oxygen affinity, high cooperativity, and stability against autoxidation, rHb (beta N108Q) is considered a potential candidate for the Hb-based oxygen carrier in a blood substitute system.
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Kanno S, Lee PC, Dodd SJ, Williams M, Griffith BP, Ho C. A novel approach with magnetic resonance imaging used for the detection of lung allograft rejection. J Thorac Cardiovasc Surg 2000; 120:923-34. [PMID: 11044319 DOI: 10.1067/mtc.2000.110184] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Although various techniques have been explored for the detection and quantification of allograft transplant rejection, a practical and reliable method that is noninvasive is still elusive. METHODS For our magnetic resonance imaging experiments, we have developed a new rat model of heterotopic lung transplantation to the inguinal region. Allogeneic transplants (DA to Brown Norway) were performed with and without cyclosporine A (INN: ciclosporin) treatment, with syngeneic transplants (Brown Norway to Brown Norway) serving as controls (n = 6 per group). Magnetic resonance images were obtained with a gradient echo method before and after injection of ultra-small superparamagnetic iron oxide particles. RESULTS At day 5, allogeneic transplants without cyclosporine A treatment showed a grade 4 rejection histologically. A significantly lower magnetic resonance signal was seen 24 hours after injection of ultra-small superparamagnetic iron oxide particles compared with the preinjection image (346 +/- 7.6 vs 839 +/- 43.4 arbitrary units; P <. 05). Syngeneic transplants showed no evidence of rejection histologically and no differences in magnetic resonance imaging signals between the images before and after injection of ultra-small superparamagnetic iron oxide particles (863 +/- 18.8 vs 880 +/- 22.5). Allotransplants treated with cyclosporine A showed a grade 2 rejection histologically. The change in magnetic resonance signals in that group was small but showed a significant decrease in signal intensity after injection (646 +/- 10.5 vs 889 +/- 23.5, P <.05). Immunohistochemistry and iron staining of the allografts indicated that ultra-small superparamagnetic iron oxide particles were taken up by the infiltrating macrophages that accumulated at the rejection site. CONCLUSIONS We have demonstrated a novel approach for the detection of acute lung allograft rejection using magnetic resonance imaging coupled with injection of ultra-small superparamagnetic iron oxide particles. Despite its limitations, our method might be a first step toward a potential clinical application.
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Lukin JA, Simplaceanu V, Zou M, Ho NT, Ho C. NMR reveals hydrogen bonds between oxygen and distal histidines in oxyhemoglobin. Proc Natl Acad Sci U S A 2000; 97:10354-8. [PMID: 10962034 PMCID: PMC27028 DOI: 10.1073/pnas.190254697] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Compared with free heme, the proteins hemoglobin (Hb) and myoglobin (Mb) exhibit greatly enhanced affinity for oxygen relative to carbon monoxide. This physiologically vital property has been attributed to either steric hindrance of CO or stabilization of O(2) binding by a hydrogen bond with the distal histidine. We report here the first direct evidence of such a hydrogen bond in both alpha- and beta-chains of oxyhemoglobin, as revealed by heteronuclear NMR spectra of chain-selectively labeled samples. Using these spectra, we have assigned the imidazole ring (1)H and (15)N chemical shifts of the proximal and distal histidines in both carbonmonoxy- and oxy-Hb. Because of their proximity to the heme, these chemical shifts are extremely sensitive to the heme pocket conformation. Comparison of the measured chemical shifts with values predicted from x-ray structures suggests differences between the solution and crystal structures of oxy-Hb. The chemical shift discrepancies could be accounted for by very small displacements of the proximal and distal histidines. This suggests that NMR could be used to obtain very high-resolution heme pocket structures of Hb, Mb, and other heme proteins.
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Zhang Y, Dodd SJ, Hendrich KS, Williams M, Ho C. Magnetic resonance imaging detection of rat renal transplant rejection by monitoring macrophage infiltration. Kidney Int 2000; 58:1300-10. [PMID: 10972694 DOI: 10.1046/j.1523-1755.2000.00286.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND A rat renal transplantation model was studied by noninvasive magnetic resonance imaging (MRI) with an infusion of ultrasmall superparamagnetic iron oxide (USPIO) particles to test whether the accumulation of immune cells, such as macrophages, could be detected in vivo while the kidney transplant was being rejected. METHODS Major histocompatibility disparate DA to BN male rat renal transplantation recipients were infused with USPIO particles, with magnetic resonance (MR) images acquired before, immediately after, and one day following infusion. RESULTS When the USPIO infusion was on the fourth day post-transplantation, some rejecting allografts showed a decrease of MR signal intensity one day later. Isografts and allografts with triple immunosuppressant treatment had no MR signal reduction. Immunohistologic staining for ED1+ macrophages and CD4+ and CD8+ T cells in allogeneic transplanted kidneys indicated the accumulation of these immune cells as acute rejection occurred. Morphological studies by electron microscopy confirmed the existence of iron inside the lysosomes of macrophages of rejecting kidneys, while Prussian blue staining detected the presence of iron plaques in macrophages. Isografts and allografts with a triple immunosuppressant treatment exhibited smaller MR signal reductions with minimal histologic changes. CONCLUSIONS The concurrence of MR signal reduction following USPIO infusion with pathological manifestation in a rat renal allograft model suggests the possibility that renal transplantation status may be assessed by MRI using USPIO particles as markers for the accumulation of immune cells, such as macrophages.
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Ip MS, Lam KS, Ho C, Tsang KW, Lam W. Serum leptin and vascular risk factors in obstructive sleep apnea. Chest 2000; 118:580-6. [PMID: 10988175 DOI: 10.1378/chest.118.3.580] [Citation(s) in RCA: 293] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
STUDY OBJECTIVES To define the metabolic profile relevant to vascular risks in obstructive sleep apnea (OSA) and the role of leptin resistance in this risk profile. DESIGN Case control study. SETTING Sleep Laboratory, Queen Mary Hospital, University of Hong Kong, China. METHODS Thirty OSA subjects were matched with 30 non-OSA subjects for body mass index (BMI), age, sex, and menopausal status. Neck, waist, and hip girth, skinfold thickness, and fasting serum levels of lipids, glucose, insulin, and leptin were compared between these two groups. RESULTS Compared with control subjects with a similar BMI but without OSA, the OSA group had a significantly more adverse vascular risk factor profile, including dyslipidemia, higher diastolic BP, insulin resistance, and greater adiposity reflected by skinfold thickness. OSA subjects also had higher circulating leptin levels (9.18+/-4.24 ng/mL vs 6.54+/-3.81 ng/mL, mean +/- SD, p = 0.001). Serum leptin levels correlated positively with BMI, skinfold thickness, serum cholesterol, low-density lipoprotein cholesterol, insulin, insulin/glucose ratio, apnea-hypopnea index, and oxygen desaturation time; multiple stepwise regression analysis identified skinfold thickness, waist/hip ratio, serum low-density lipoprotein cholesterol, and diastolic BP as independent correlates, while only serum insulin and diastolic BP were independent correlates in OSA subjects. After treatment with nasal continuous positive airway pressure for 6 months, there was a significant decrease in circulating leptin (p = 0.01) and triglyceride levels (p = 0.02) without change in other parameters. CONCLUSION Despite controlling for BMI, OSA subjects showed distinct profiles with clustering of vascular risk factors. Hyperleptinemia was present in the OSA subjects, but it can be normalized by treatment with nasal continuous positive airway pressure, suggesting that increased leptin resistance was not the cause of OSA or its associated vascular risks.
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Dym O, Pratt EA, Ho C, Eisenberg D. The crystal structure of D-lactate dehydrogenase, a peripheral membrane respiratory enzyme. Proc Natl Acad Sci U S A 2000; 97:9413-8. [PMID: 10944213 PMCID: PMC16878 DOI: 10.1073/pnas.97.17.9413] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
d-Lactate dehydrogenase (d-LDH) of Escherichia coli is a peripheral membrane respiratory enzyme involved in electron transfer, located on the cytoplasmic side of the inner membrane. d-LDH catalyzes the oxidation of d-lactate to pyruvate, which is coupled to transmembrane transport of amino acids and sugars. Here we describe the crystal structure at 1.9 A resolution of the three domains of d-LDH: the flavin adenine dinucleotide (FAD)-binding domain, the cap domain, and the membrane-binding domain. The FAD-binding domain contains the site of d-lactate reduction by a noncovalently bound FAD cofactor and has an overall fold similar to other members of a recently discovered FAD-containing family of proteins. This structural similarity extends to the cap domain as well. The most prominent difference between d-LDH and the other members of the FAD-containing family is the membrane-binding domain, which is either absent in some of these proteins or differs significantly. The d-LDH membrane-binding domain presents an electropositive surface with six Arg and five Lys residues, which presumably interacts with the negatively charged phospholipid head groups of the membrane. Thus, d-LDH appears to bind the membrane through electrostatic rather than hydrophobic forces.
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