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Chen CT, Chan JY, Barnes CD, Chan SH. Tonic suppression of baroreceptor reflex by endogenous neurotensin in the rat. REGULATORY PEPTIDES 1990; 28:23-37. [PMID: 2326505 DOI: 10.1016/0167-0115(90)90061-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We evaluated the modulatory role of endogenous neurotensin (NT) in baroreceptor reflex (BRR) response in Sprague-Dawley rats anesthetized with pentobarbital sodium. Intracerebroventricular (i.c.v.) administration of NT (15 or 30 nmol) significantly reduced the sensitivity of the BRR response. Blocking the endogenous activity of the tridecapeptide with its specific antagonist, (D-Trp11)-NT (4 or 8 nmol) or antiserum against NT (1:20); or inhibiting the aminopeptidases with bestatin (200 nmol), on the other hand, promoted a potentiation of BRR response. When administered together with bestatin (200 nmol), the suppressive effect of NT (15 nmol) on the BRR response was further enhanced, as was the augmentative action of (D-Trp11)-NT (4 nmol). Upon microinjection into the bilateral nucleus tractus solitarius (NTS), NT (600 pmol) and (D-Trp11)-NT (150 pmol) respectively elicited a reduction and enhancement of the BRR response. These results suggest that neurons that contain NT may participate in central cardiovascular regulation by tonically suppressing the BRR, possibly via an action on the NTS where baroreceptor afferents terminate.
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Shapiro ET, Cooper M, Chen CT, Given BD, Polonsky KS. Change in hexose distribution volume and fractional utilization of [18F]-2-deoxy-2-fluoro-D-glucose in brain during acute hypoglycemia in humans. Diabetes 1990; 39:175-80. [PMID: 2227124 DOI: 10.2337/diab.39.2.175] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We used positron emission tomography (PET) to study the effects of mild hypoglycemia on cerebral glucose uptake and metabolism. Nine healthy men were studied under basal saline-infusion conditions, and during euglycemic and hypoglycemic clamp studies. Insulin was infused at the same rate (1 mU.kg-1.min-1) in both clamp studies. In euglycemic clamp studies, glucose was infused at a rate sufficient to maintain the basal plasma glucose concentration, whereas in hypoglycemic clamp studies, the glucose infusion rate was reduced to maintain the plasma glucose at 3.1 mM. Each study lasted 3 h and included a 30-min baseline period and a subsequent 150-min period in which insulin or glucose was administered. Blood samples for measurement of insulin, glucose, cortisol, growth hormone, and glucagon were obtained at 20- to 30-min intervals. A bolus injection of 5-10 mCi [18F]-2-deoxy-2-fluoro-D-glucose (2-DFG) was administered 120 min after initiation of the study, and plasma radioactivity and dynamic PET scans were obtained at frequent intervals for the remaining 40-60 min of the study. Cerebral regions of interest were defined, and concentrations of radioactivity were calculated and used in the three-compartment model of 2-DFG distribution described by Sokoloff. Glucose levels were similar during saline-infusion (4.9 +/- 0.1 mM) and euglycemic clamp (4.8 +/- 0.1 mM) studies, whereas the desired degree of mild hypoglycemia was achieved during the hypoglycemic clamp study (3.1 +/- 0.1 mM, P less than 0.05). The insulin level during saline infusion was 41 +/- 7 pM.(ABSTRACT TRUNCATED AT 250 WORDS)
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Mukherjee J, Luh KE, Yasillo N, Perry BD, Levy D, Chen CT, Ortega C, Beck RN, Cooper M. Dopamine D-2 receptors imaged by PET in Cebus apella using [18F]benzamide neuroleptic. Eur J Pharmacol 1990; 175:363-4. [PMID: 2323353 DOI: 10.1016/0014-2999(90)90578-t] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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254
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Chen SY, Lin WC, Liang CC, Chen CT. Improvement on dynamic elastic interpolation technique for reconstructing 3-D objects from serial cross sections [biomedical application]. IEEE TRANSACTIONS ON MEDICAL IMAGING 1990; 9:71-83. [PMID: 18222752 DOI: 10.1109/42.52984] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
An improved method for automatically reconstructing a three-dimensional object from serial cross sections is presented. The method improves the dynamic elastic contour interpolation technique. There are two major improvements: (1) in the case of branching that involves concave contours, instead of pairwise interpolation between the start contour and each goal contour, the goal image is considered globally and local constraints are imposed on the forces exerting upon the vertices; and (2) it takes the continuity of high-order derivatives into consideration and incorporates the schemes of spline theory, quadratic-variation-based surface interpolation, and finite-element-based multilevel surface interpolation to create smoother surfaces of the reconstructed object. Based on the output from the preliminary processing, two alternatives, a quadratic-variation-based surface interpolation algorithm and a finite-element-based multilevel surface interpolation algorithm, can be adopted to obtain the final surface representation.
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Chen CT, Ma Y, Sette F. K-shell photoabsorption of the N2 molecule. PHYSICAL REVIEW. A, GENERAL PHYSICS 1989; 40:6737-6740. [PMID: 9902078 DOI: 10.1103/physreva.40.6737] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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256
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Ma Y, Sette F, Meigs G, Modesti S, Chen CT. Breaking of ground-state symmetry in core-excited ethylene and benzene. PHYSICAL REVIEW LETTERS 1989; 63:2044-2047. [PMID: 10040748 DOI: 10.1103/physrevlett.63.2044] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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257
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Chen CT, Smith NV. Unoccupied surface states on clean and oxygen-covered Cu(110) and Cu(111). PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 40:7487-7490. [PMID: 9991171 DOI: 10.1103/physrevb.40.7487] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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258
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Smith NV, Chen CT, Weinert M. Distance of the image plane from metal surfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 40:7565-7573. [PMID: 9991183 DOI: 10.1103/physrevb.40.7565] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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259
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Levin DN, Hu XP, Tan KK, Galhotra S, Pelizzari CA, Chen GT, Beck RN, Chen CT, Cooper MD, Mullan JF. The brain: integrated three-dimensional display of MR and PET images. Radiology 1989; 172:783-9. [PMID: 2788893 DOI: 10.1148/radiology.172.3.2788893] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Three patients with intractable epilepsy, two with brain tumors, and one with encephalitis were imaged with magnetic resonance (MR) and positron emission tomography (PET). MR data were used to construct a three-dimensional (3D) computer model of the brain surface depicting the precentral (movement), postcentral (sensation), left inferior frontal (speech), and left superior temporal (hearing) gyri. PET-derived measurements of average surface metabolism were encoded as colors and mapped onto the 3D model by means of a retrospective technique for registering the two scans. The integrated 3D model depicted the location of PET-detected metabolic abnormalities with respect to the gyral anatomy visualized with MR. In each case, the predicted relationships were confirmed intraoperatively by means of inspection of the brain and electroencephalography. Multimodality 3D displays are likely to be particularly valuable for interpreting PET studies of epileptic patients and others with normal MR anatomy.
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Chang WH, Lin SK, Jann MW, Lam YW, Chen TY, Chen CT, Hu WH, Yeh EK. Pharmacodynamics and pharmacokinetics of haloperidol and reduced haloperidol in schizophrenic patients. Biol Psychiatry 1989; 26:239-49. [PMID: 2742942 DOI: 10.1016/0006-3223(89)90036-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Twelve male chronic schizophrenic inpatients, neuroleptic-free for at least 4 weeks, were given an oral test dose of 10 mg haloperidol (HAL) and reduced HAL (RHAL) in a random order, with a 2-week interval. Two weeks after the last test dose, the patients were given HAL, 5 mg orally twice daily for 7 days. Blood samples were drawn at baseline and between 0.5 and 24 hr after the test doses, and during HAL treatment as well. Plasma drug concentrations and homovanillic acid (HVA) levels were measured with high-performance liquid chromatography using electrochemical detection. HAL, but not RHAL, produced increments in plasma HVA (pHVA) levels at 24 hr after a test dose. pHVA levels remained higher than baseline during HAL treatment. Detectable interconversion between HAL and RHAL was observed in eight patients. The capacity of the reductive drug-metabolizing enzyme system, however, was greater than that of the oxidative processes. The plasma RHAL:HAL ratios on days 6 and 7 were higher than and positively correlated with those at Tmax after a single dose of HAL and were negatively correlated with the HAL:RHAL ratios at Tmax after a single dose of RHAL. Thus, both reductive and oxidative drug-metabolizing systems probably contribute to individual differences in plasma RHAL:HAL ratios in HAL-treated schizophrenic patients.
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261
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Sette F, Sinkovic B, Ma YJ, Chen CT. Crystal-field splitting of core excitons in ionic crystals. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:11125-11130. [PMID: 9947927 DOI: 10.1103/physrevb.39.11125] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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262
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Murphy R, Plummer EW, Chen CT, Eberhardt W, Carr R. Dynamics of adsorbate core-hole decay. II. Lifetimes. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:7517-7521. [PMID: 9947430 DOI: 10.1103/physrevb.39.7517] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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263
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Pelizzari CA, Chen GT, Spelbring DR, Weichselbaum RR, Chen CT. Accurate three-dimensional registration of CT, PET, and/or MR images of the brain. J Comput Assist Tomogr 1989; 13:20-6. [PMID: 2492038 DOI: 10.1097/00004728-198901000-00004] [Citation(s) in RCA: 505] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A surface matching technique has been developed to register multiple imaging scans of the brain in three dimensions, with accuracy on the order of the image pixel sizes. Anatomic information visualized in X-ray CT and magnetic resonance images may be integrated with each other and with functional information from positron emission tomography. Anatomical structures and other volumes of interest may be mapped from one scan to another, and corresponding sections through multiple scans may be directly compared. This capability provides a novel quantitative method to address the fundamental problem of relating structure to function in the brain. Applications include basic and clinical problems in the neurosciences and delivery and assessment of brain tumor therapy.
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264
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Levin DN, Pelizzari CA, Chen GT, Chen CT, Cooper MD. Retrospective geometric correlation of MR, CT, and PET images. Radiology 1988; 169:817-23. [PMID: 3263666 DOI: 10.1148/radiology.169.3.3263666] [Citation(s) in RCA: 140] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Magnetic resonance imaging, computed tomographic, and positron emission tomographic studies of the brain provide complementary information, and many patients undergo more than one of these studies during the course of their diagnostic workup and treatment. A new technique for quantitative geometric correlation of such studies makes it possible to create integrated multimodality images by mapping features from one image onto an image obtained with another modality. The coordinate transformation between any pair of images is found by a semiautomatic algorithm for matching models of the patient's external surface as depicted in the two data sets. The resultant hybrid images, which combine complementary features of different studies, are often more useful for diagnosis and treatment planning than are the original single-modality images. The algorithm can also be used for spatial registration of baseline studies with follow-up images created with the same modality, which allows tracking of a lesion to detect subtle interval changes in size and shape. This technique can be applied to images acquired in routine clinical practice, since it is completely retrospective and does not necessitate special positioning or landmarking of the patient.
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265
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Siebers RW, Chen CT, Ferguson RI, Maling TJ. Effect of blood sample tubes on amiodarone and desethylamiodarone concentrations. Ther Drug Monit 1988; 10:349-51. [PMID: 3176114 DOI: 10.1097/00007691-198803000-00020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have investigated the change in amiodarone and desethylamiodarone concentrations in blood sampled from three different Vacutainer tubes: (a) sodium heparin, (b) gel separator (SST), and (c) no additive (plain tube). Amiodarone and desethylamiodarone concentrations were determined by a reverse-phase high pressure liquid chromatography technique in samples from 12 subjects on chronic amiodarone therapy. Amiodarone concentrations were significantly lower in plasma compared with serum from either gel separator (11.5%, p = 0.05) or no additive (13.5%, p = 0.01) tubes. Desethylamiodarone concentrations were significantly lower in plasma compared with serum from gel separator tubes (8.5%, p = 0.04) and were slightly lower compared with no additive tubes (4.4%, p = 0.41). Serum amiodarone and desethylamiodarone concentrations from either no additive or gel separator tubes yielded similar results. We conclude that significant amiodarone and desethylamiodarone concentration differences occur between serum and plasma, and that no binding of amiodarone and desethylamiodarone to the separator gel occurs.
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266
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Chen CT, Dineen H, Newton JD. Specificity of different substrates used in three amylase assays. Clin Chem 1988; 34:1363-4. [PMID: 2454169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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267
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Chen CT, Dineen H, Newton JD. Specificity of different substrates used in three amylase assays. Clin Chem 1988. [DOI: 10.1093/clinchem/34.6.1363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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268
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269
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Ford WK, Chen CT, Anderson J, Kwo J, Liou SH, Hong M, Rubenacker GV, Drumheller JE. Oxygen defect in YBa2Cu. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 37:7924-7927. [PMID: 9944113 DOI: 10.1103/physrevb.37.7924] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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270
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Chang YS, Huang FL, Chen CT, Lo TB. Isolation and properties of the pituitary gonadotropin from silver carp (Hypophthalmichthys molitrix). INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1988; 31:150-6. [PMID: 3366548 DOI: 10.1111/j.1399-3011.1988.tb00017.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The gonadotropin of silver carp (scGTH) was purified from the pituitary glands in a yield of 8.4 mg/g through extraction with 6% ammonium acetate (pH 5.1)-40% ethanol followed by 80% ethanol precipitation, DEAE-cellulose chromatography and gel filtration. The molecular weight of scGTH is about 32,000 as estimated by gel filtration. Leucine and serine were the two N-termini of scGTH. The amino acid composition of scGTH is rich in aspartic acid/asparagine, glutamic acid/glutamine, valine, proline and half cystine. Its carbohydrate content is 22.2%. Biologically, scGTH significantly stimulated the steroidogenesis in carp testis and ovary in vitro and induced the ovulation in loaches. It also stimulated the 32P-phosphate uptake into 1-day-old chicken testis. Immunologically, scGTH could cross-react with the antiserum against cGTH and vice versa. In both cases parallel displacement curves were displayed.
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271
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Chen CT, Sette F. Comment on "Determination of interface states for CaF2/Si(111) from near-edge x-ray-absorption measurements". PHYSICAL REVIEW LETTERS 1988; 60:160. [PMID: 10038224 DOI: 10.1103/physrevlett.60.160] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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272
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Chen CT. The EMIT-St system adapted for use in the CentrifiChem 400. Clin Chem 1988. [DOI: 10.1093/clinchem/34.1.181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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273
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Chen CT. The EMIT-St system adapted for use in the CentrifiChem 400. Clin Chem 1988; 34:181-2. [PMID: 3276415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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274
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Lin WC, Liang CC, Chen CT. Dynamic elastic interpolation for 3D medical image reconstruction from serial cross sections. IEEE TRANSACTIONS ON MEDICAL IMAGING 1988; 7:225-232. [PMID: 18230473 DOI: 10.1109/42.7786] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
An interpolation method is proposed for generating the intermediate contours between a start contour and a goal contour. Coupled with the display method for voxel-based objects, it provides a powerful tool for reconstructing the 3D object from serial cross sections. The method tries to fill in the lost information between two slices, assuming that there is smooth change between them. This is a reasonable assumption provided that the sampling is at least twice the Nyquist rate, in which case the result of the interpolation is expected to be very close to reality. One of the major advantages of this approach is its ability to handle the branching problem. Another major advantage is that after each intermediate contour is generated and sent to display device, there is no need to keep it in the memory unless the solid model will be used for further processing. Thus, the space complexity of this algorithm is relatively low.
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275
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Powell GF, Chen CT. Radiation absorbed dose to bladder walls from positron emitters in the bladder content. Med Phys 1987; 14:1079-86. [PMID: 3501064 DOI: 10.1118/1.595988] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A method to calculate absorbed doses at depths in the walls of a static spherical bladder from a positron emitter in the bladder content has been developed. The beta ray dose component is calculated for a spherical model by employing the solutions to the integration of Loevinger and Bochkarev point source functions over line segments and a line segment source array technique. The gamma ray dose is determined using the specific gamma ray constant. As an example, absorbed radiation doses to the bladder walls from F-18 in the bladder content are presented for static spherical bladder models having radii of 2.0 and 3.5 cm, respectively. Experiments with ultra-thin thermoluminescent dosimeters (TLD's) were performed to verify the results of the calculations. Good agreement between TLD measurements and calculations was obtained.
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276
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Sette F, Chen CT, Rowe JE, Citrin PH. Are surface-atom vibrational amplitudes along the normal always larger than in the plane? PHYSICAL REVIEW LETTERS 1987; 59:311-314. [PMID: 10035728 DOI: 10.1103/physrevlett.59.311] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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277
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Chen CT, Smith NV. Energy dispersion of image states and surface states near the surface-Brillouin-zone boundary. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 35:5407-5412. [PMID: 9940747 DOI: 10.1103/physrevb.35.5407] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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278
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Toung TJ, Donham RT, Chen CT. Topical tracheal anesthesia can be administered through a catheter attached to the endotracheal tube. Anesth Analg 1986; 65:315. [PMID: 3954100 DOI: 10.1213/00000539-198603000-00021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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279
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Eberhardt W, Plummer EW, Chen CT, Ford WK. Deexcitation Electron Spectroscopy: A Probe for the Localisation of Valence Wavefunctions in Free and Adsorbed Molecules. ACTA ACUST UNITED AC 1986. [DOI: 10.1071/ph860853] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Deexcitation electron spectroscopy (DES) is the measurement of the kinetic energy distribution of electrons emitted in the decay of highly excited states of molecules formed by core to bound resonant photon absorption. This spectroscopy has the potential of becoming a new probe of the localised properties of the valence electronic states in molecules as well as furnishing new insights into the dynamics of the electronic decay and screening processes. This paper describes the basic principles of DES by following the evolution of the DES spectra in CO, from the isolated CO molecule in the gas phase, through the transition metal carbonyls, to CO adsorbed on a surface. In all three cases the energetics, intensities and dynamics of DES will be compared with photoelectron spectroscopy (PES) and Auger electron spectroscopy (AES).
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280
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Chen CT, DiDio RA, Ford WK, Plummer EW, Eberhardt W. Dynamics of adsorbate core-hole decay. PHYSICAL REVIEW. B, CONDENSED MATTER 1985; 32:8434-8437. [PMID: 9937044 DOI: 10.1103/physrevb.32.8434] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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281
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Chen CT, Toung TJ, Nora S, Cameron JL. Concerning the actions and efficacy of different antacids. Anesthesiology 1985; 62:544-5. [PMID: 3985413 DOI: 10.1097/00000542-198504000-00038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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282
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Chen CT, Toung TJ, Rogers MC. Effect of intra-alveolar meconium on pulmonary surface tension properties. Crit Care Med 1985; 13:233-6. [PMID: 3979070 DOI: 10.1097/00003246-198504000-00005] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
To evaluate the effect of meconium on pulmonary surface tension properties, the mechanics of 30 excised, separated canine pulmonary lobes were studied. Meconia were blended in normal saline to produce solutions of 10% and 20%. Solutions were filtered to remove large particles and instilled endobronchially into the canine lobes. The static pressure-volume deflation curve of each lobe was determined before and 4 h after instillation of either normal saline or meconium solution. In the saline control group (eight lobes), the curve was essentially unchanged before and after instillation. In the 10% meconium group (14 lobes), the curve was significantly depressed after instillation, especially at a transpulmonary airway pressure of 10 cm H2O (p less than .05) and 5 cm H2O (p less than .005). In the 20% meconium group (eight lobes), the depression of the pressure-volume curve was essentially the same as that of the 10% solution group. It is concluded that meconium depresses the surface-active properties of the alveolar linings.
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283
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Chan HP, Chen CT, Doi K, Fewell TR, Shuping RE. Investigation of energy responses of germanium detectors and correction of measured spectra by means of Monte Carlo simulation. Radiat Res 1984; 99:443-64. [PMID: 6473707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A Monte Carlo program was developed which determines the energy response of X-ray detectors of various "nested" sizes simultaneously. Twenty-one planar germanium detectors with cylindrical crystals were chosen, which are commercially available for X-ray spectrometry. The photopeak efficiency, K alpha and K beta escape fractions. Compton fraction, elastic fraction, penetration fraction, and the Compton continuum were tabulated as a function of incident X-ray energies from 12 to 300 keV in 2-keV increments. Coefficients of polynomials fitted to the Compton continua were also calculated to facilitate computer implementation of spectrum corrections. Spectrum correction methods which use the Compton continua determined by Monte Carlo calculation were compared with those approximated by rectangles. Comparison of the residual root-mean-square (RRMS) values between the incident and corrected spectra showed that the former method yielded lower RRMS values. However, the differences in these values are small, indicating that the simple rectangular approximation may be adequate for most spectral measurements.
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284
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Dill CW, Chen CT, Alford ES, Edwards RL, Richter RL, Garza C. Lipolytic Activity During Storage of Human Milk: Accumulation of Free Fatty Acids 1. J Food Prot 1984; 47:690-693. [PMID: 30934443 DOI: 10.4315/0362-028x-47.9.690] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Lipolysis was quantitated during storage of fluid and freezedried human whole and skim milks. Fatty acid accumulation was faster in whole fluid milk stored for 1 week at 4°C than in frozen (-20°C) samples stored for 180 d. The rapid accumulation of fatty acids during 24 h of storage at 4°C was enhanced in previously frozen milk samples. While freeze-dried whole milk showed no lipolysis when stored at -20°C, accumulation of free fatty acids was rapid in samples stored at room temperature. Fluid and freeze-dried skim milk samples exhibited no appreciable lipolysis.
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285
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Chen CT, Toung TJ, Haupt HM, Hutchins GM, Cameron JL. Evaluation of the efficacy of Alka-Seltzer Effervescent in gastric acid neutralization. Anesth Analg 1984; 63:325-9. [PMID: 6703349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A commercially available antacid, a mixture of sodium and potassium bicarbonates and citric acid (Alka-Seltzer Effervescent), was evaluated experimentally and clinically for its efficacy in neutralizing 0.1 N HCl and gastric contents. In an in vitro titration study, Alka-Seltzer Effervescent buffered 5-30 times the volume of HCl with a pH between 1.0 and 2.0 to above a pH of 2.5. In an isolated canine pulmonary lobe model, aspiration of the antacid or acid-antacid mixture caused only a mild increase in lobe weight and did not increase intrapulmonary shunting. In the clinical study, when the antacid was given 5-40 min before administration of general anesthesia in a group of patients for emergency surgery, the pH of the gastric contents in each patient was increased to above 4.0. This contrasts with the control group of patients, which showed 50% (P less than 0.05) of the patients were at risk when no antacid was administered. Preoperative administration of Alka-Seltzer effectively increases the pH of the gastric contents in patients undergoing emergency surgery.
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Dill CW, Chen CT, Alford ES, Edwards RL, Richter RL, Garza C. Lipolytic Activity During Storage of Human Milk: Stability of the Bile Salt-Stimulated Lipase 1. J Food Prot 1983; 46:994-996. [PMID: 30921858 DOI: 10.4315/0362-028x-46.11.994] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bile salt-stimulated lipase activity was monitored in fresh human milk and skim milk during refrigerated (4°C) and frozen (-20°C) storage, and in the lyophilized milks stored at -20°C and at room temperature. Following a sharp initial drop to approximately 77% of the original lipase activity, lipase was relatively stable in frozen or freeze-dried milks during 180 d of storage at -20°C. Activity losses were greatest (P < .05) in freeze-dried whole milks and skim milks stored at room temperature, approximating a 30% loss during 30 d of storage. Lipase activity was stable during refrigerated (4°C) storage of whole milk for 1 week.
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Swindell W, Simpson RG, Oleson JR, Chen CT, Grubbs EA. Computed tomography with a linear accelerator with radiotherapy applications. Med Phys 1983; 10:416-20. [PMID: 6412044 DOI: 10.1118/1.595391] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
An earlier paper [Simpson et al., Med. Phys. 9, 574 (1982)] described a computed tomography (CT) scanner that was constructed by adding a detector array to a 4-MV isocentric linear accelerator. Since the previous article, the detector array has been improved and we now demonstrate better than 3-mm spatial resolution and better than 1% relative electron density discrimination. A series of pictures from volunteer patients is included. Normal anatomy is visualized with bone, muscle, fat, and air being clearly delineated.
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Schmidt RA, Chan HP, Kodera Y, Doi K, Chen CT. Evaluation of cassette performance: physical factors affecting patient exposure and image contrast. Radiology 1983; 146:801-6. [PMID: 6828696 DOI: 10.1148/radiology.146.3.6828696] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Physical properties of four radiographic cassettes were investigated in combination with various screen/film systems. These properties included (a) transmittance of monoenergetic x rays over 14-96 keV and comparison with predictions based on attenuation coefficients; (b) relative patient exposure from 60 to 120 kV (from phantom measurements) and correlation with predictions based on measured transmittance as well as average energies and angles of incident radiation; and (c) amounts of scatter from various cassette materials and comparison with Monte Carlo calculations. The results provide a model of performance based on quantitation of cassette effects on system speed and image contrast. Carbon-fiber cassettes required the lowest patient exposure, produced the least scatter, and (in low-scatter situations) were capable of increased image contrast.
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289
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Simpson RG, Chen CT, Grubbs EA, Swindell W. A 4-MV CT scanner for radiation therapy: the prototype system. Med Phys 1982; 9:574-9. [PMID: 7110089 DOI: 10.1118/1.595102] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
A Varian 4-MV isocentric therapy accelerator has been modified to perform also as a CT scanner. The goal is to provide a computed tomography capability for use in radiotherapy at low cost. We envision three principal uses for the system. These are (i) to provide two and three-dimensional maps of electron density distribution for CT assisted therapy planning; (ii) to aid in patient set up by providing sectional views of the treatment volume and high contrast scout-mode verification images; and (iii) to provide a means for periodically checking the patients anatomical conformation against that which was used to generate the original therapy plan. The machine was modified by mounting an array of detectors on a frame that is bolted to the counterweight end of the gantry in such a manner as to define a "third generation" CT scanner geometry. Details of the detectors and data acquisition electronics are provided. We present results of phantom studies which demonstrate that this prototype system has a spatial resolution of 4 mm and the ability to discriminate electron density differences of less than 1%. We also show that the system is exactly linear over a wide range of electron densities corresponding to those found in body tissues.
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Murnane JP, Byfield JE, Chen CT, Wang CH. The structure of methylated xanthines in relation to their effects on DNA synthesis and cell lethality in nitrogen mustard-treated cells. Biophys J 1981; 35:665-76. [PMID: 7272456 PMCID: PMC1327555 DOI: 10.1016/s0006-3495(81)84819-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The variation in cellular response to alkylated xanthines possessing different side chains has been used to evaluate more fully the effect of caffeine on both survival and DNA synthesis in cells with DNA damage. A correlation is observed between the ability of these xanthines to reverse the inhibitory effects of nitrogen mustard damage on DNA synthesis and their ability to enhance nitrogen mustard lethality in human HT-29 cells. These findings are consistent with our theory that regulation of damaged replicon initiation protects against potentially lethal damage in the form of unrepaired DNA alkylations. Enhancement of nitrogen mustard lethality is observed to have a maximum limit, which can be reduced by highly toxic xanthine concentrations. The lethal effects of xanthines alone at higher concentrations are unrelated to the effects of caffeine specific to nitrogen mustard treated cells, and appear to be related to an immediate reduction in thymidine incorporation most likely caused by inhibition of other enzyme systems influencing DNA synthesis such as de novo and salvage pathways for purine biosynthesis.
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Abstract
Simple mass-balance calculations indicate that in seawater the calcium variation (DeltaCa) correlates with the variation in the titration alkalinity (DeltaTA) and the variation in the total carbon dioxide (DeltasigmaCO(2)) or nitrate (DeltaNO(3)) according to the equations DeltaCa = 0.46288 DeltaTA + 0.074236 DeltasigmaCO(2) and DeltaCa = 0.5 DeltaTA + 0.53125 DeltaNO(3). The estimated values for DeltaCa from these equations, which agree with the values obtained from direct measurements, have been used to estimate the ratio of the in situ inorganic to organic carbon fluxes in the oceans. The precise vertical distribution of this ratio is shown for the first time.
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Chen CT, Kodama H, Egashira Y, Samejima K, Imanari T, Tamura Z. Serum levels of 5-chloro-7-iodo-8-quinolinol and its toxicity in various animals. Chem Pharm Bull (Tokyo) 1976; 24:2007-13. [PMID: 825234 DOI: 10.1248/cpb.24.2007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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294
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Ferris JP, Chen CT. Chemical evolution. XXVI. Photochemistry of methane, nitrogen, and water mixture as a model for the atmosphere of the primitive earth. J Am Chem Soc 1975; 97:2962-7. [PMID: 1133344 DOI: 10.1021/ja00844a007] [Citation(s) in RCA: 44] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Chen CT, Nakanishi K, Natori S. Biosynthesis of elsinochrome A, the perylenequinone from Elsinoë spp. I. Chem Pharm Bull (Tokyo) 1966; 14:1434-7. [PMID: 5981250 DOI: 10.1248/cpb.14.1434] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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296
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