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Plant MJ, Williams AL, O'Sullivan MM, Lewis PA, Coles EC, Jessop JD. Relationship between time-integrated C-reactive protein levels and radiologic progression in patients with rheumatoid arthritis. ARTHRITIS AND RHEUMATISM 2000; 43:1473-7. [PMID: 10902748 DOI: 10.1002/1529-0131(200007)43:7<1473::aid-anr9>3.0.co;2-n] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE An elevated acute-phase response is associated with increased radiologic damage in rheumatoid arthritis (RA), but development of damage in previously normal joints ("new joint involvement") has not previously been investigated. This study was undertaken to investigate the hypothesis that when there is suppression of disease activity as judged by the C-reactive protein level, new joint involvement is reduced to a greater extent than is progression in already damaged joints ("damaged joint progression"). METHODS Three hundred fifty-nine patients with active RA were studied as part of a 5-year randomized, prospective, open-label study of disease-modifying antirheumatic drug therapy. Time-averaged CRP was calculated from samples obtained every 6 months, and patients were divided into groups with CRP values of <6, 6-<12, 12-<25, and > or =25 mg/liter. Radiographs of the hands and feet were scored by the Larsen method; a damaged joint was defined as one with a score of > or =2. RESULTS The rank correlation between time-integrated CRP and increase in Larsen score was 0.50; the correlation increased to 0.59 for patients entering the study with disease duration of < or =2 years. The percentage of new joint involvement over 5 years varied markedly with time-integrated CRP, from 7.3% in the CRP <6 mg/liter group to 39.1% in the CRP > or =25 mg/liter group (5.4-fold increase). The percentage of damaged joint progression increased from 26.1% in the CRP <6 mg/liter group to 41.6% in the CRP > or =25 mg/liter group (1.6-fold increase). CONCLUSION The results of this study provide further confirmation that high CRP levels over time are associated with greater radiologic progression. Although radiologic progression still occurred in both previously normal and damaged joints despite the presence of normal CRP levels, this consisted of proportionately less new joint involvement compared with damaged joint progression. These findings support the idea that disease-suppressive therapy should be instituted at an early stage in patients with RA, before erosive damage has occurred.
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Khajotia SS, Mackert JR, Twiggs SW, Russell CM, Williams AL. Elimination, via high-rate laser dilatometry, of structural relaxation during thermal expansion measurement of dental porcelains. Dent Mater 1999; 15:390-6. [PMID: 10863437 DOI: 10.1016/s0109-5641(99)00062-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVES Thermal expansion measurement of glassy materials is complicated by thermal history effects. Excess volume--trapped in quenched dental porcelains after firing--collapses via structural relaxation on first slow heating during conventional dilatometry, making the thermal expansion coefficient (alpha) obtained on first heating unreliable. The purpose of this study was to determine whether porcelain thermal expansion measurement at high thermal rates could minimize the influence of thermal history. METHODS Eight thermal expansion specimens each of six body porcelains and the Component No. 1 (leucite-containing) frit prepared according to the patent by Weinstein et al. (US Patent No. 3,052,982) were subjected to three heat-cool conventional dilatometry runs at 3 degrees C/min, while eight thermal expansion specimens of each porcelain were reserved as untreated controls. Eight hollow, cylindrical specimens of the same brands were subjected to three heat-cool laser dilatometer thermal expansion runs at 600 degrees C/min, while eight cylindrical specimens of each porcelain were reserved as untreated controls. Thermal expansion data (25-500 degrees C) of all specimens were subjected to repeated measures analysis of variance. RESULTS The alpha obtained on first slow heating was significantly lower than values for succeeding slow heat and cool runs in all porcelains (P < 0.001). High-rate alpha obtained on first heating was not significantly different from values of succeeding heat and cool runs in all porcelains (P > 0.05). SIGNIFICANCE Conventional dilatometer measurements demonstrated occurrence of structural relaxation, as evidenced by the significant difference in the first heating and subsequent runs. High-rate laser dilatometry eliminated structural relaxation, thereby providing a thermal expansion measurement that is free of interference from thermal history effects.
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Beduschi R, Beduschi MC, Wojno KJ, Jhung M, Williams AL, Wolf JS. Antifibrinolytic additives to fibrin glue for laparoscopic wound closure in urinary tract. J Endourol 1999; 13:283-7. [PMID: 10405907 DOI: 10.1089/end.1999.13.283] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Fibrinolytic activity of urine may rapidly degrade fibrin glue used in the urinary tract, thereby limiting tissue adhesion. The goals of this study were to verify the ability of antifibrinolytic agents to delay the degradation of fibrin glue in the urinary tract and to assess the results of this delay on subsequent wound healing. MATERIALS AND METHODS In 25 domestic pigs, a 3.5-cm incision in the urinary bladder was left open (N = 6) or closed laparoscopically with fibrin glue alone (N = 6), fibrin glue containing aprotinin 5000 KIU/mL (N = 6), or fibrin glue containing aprotinin 2500 KIU/mL with (N = 4) or without (N = 3) aminocaproic acid 12.5 mg/mL. At harvest 7 days later, the bladder was tested for leakage. Histologic features were scored by a pathologist blinded to the closure method. RESULTS There were no significant differences among the groups in the amount of leakage at harvest. Significant fibrin glue material in the wound was noted more often in the pigs treated with fibrin glue plus aprotinin (7 of 13) than in the fibrin glue-only group (0 of 6; P = 0.04). The presence of significant fibrin material in the wound correlated well with absence of granulation tissue (P < 0.001), such that granulation tissue bridging the wound edges was found more often in the fibrin glue-only group (6 of 6) than in the groups treated with fibrin glue plus aprotinin (4 of 13; P = 0.01). CONCLUSIONS Although aprotinin +/- aminocaproic acid did delay the degradation of fibrin glue used to close a bladder wound, it was associated with inhibition of granulation tissue in the glued wound. These findings suggest that aprotinin alone and aprotinin plus aminocaproic acid are not useful additives to fibrin glue used for wound closure in the urinary tract.
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Beduschi R, Beduschi MC, Williams AL, Wolf JS. Pneumoperitoneum does not potentiate the nephrotoxicity of aminoglycosides in rats. Urology 1999; 53:451-4. [PMID: 9933077 DOI: 10.1016/s0090-4295(98)00498-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES Pneumoperitoneum is associated with transient renal dysfunction. To our knowledge, the safety of administering nephrotoxins such as aminoglycosides during pneumoperitoneum has not been studied. Our hypothesis was that pneumoperitoneum potentiates the nephrotoxicity of aminoglycosides. METHODS From 29 rats we obtained preprocedure 24-hour urine collections. In the pneumoperitoneum group (n = 7), carbon dioxide was insufflated intra-abdominally at 15 mm Hg pressure for 2 hours. In the gentamicin group (n = 7), 10 mg/kg gentamicin was administered intravenously. In the combined pneumoperitoneum/gentamicin group (n = 8), the same dose of gentamicin was administered 10 minutes before pneumoperitoneum. Sham rats (n = 7) received anesthesia only. Urine was collected for the 24 hours after the procedure, and 1 week later blood for creatinine determination and final 24-hour urine collections were obtained. All urine samples were assayed for creatinine and N-acetyl-beta-glucosaminidase (NAG). RESULTS Only the gentamicin and combined pneumoperitoneum/gentamicin groups presented day 1 values for NAG excretion that were significantly greater than same day sham or paired preprocedure values; the rest of the urinary creatinine and NAG day 1 levels and all the day 7 levels were not significantly different from same day sham or paired preprocedure levels. Day 7 serum creatinine and creatinine clearance did not differ significantly among the groups. CONCLUSIONS We found that intravenous gentamicin transiently increased urinary excretion of NAG in rats, which resolved within 1 week. Pneumoperitoneum for 2 hours at 15 mm Hg did not increase urinary NAG, either alone or in gentamicin-treated rats. Moreover, our data are sufficient to refute with 95% certainty the possibility that gentamicin plus pneumoperitoneum decreases creatinine clearance more than approximately 60%. These results do not support the hypothesis that pneumoperitoneum potentiates the nephrotoxicity of aminoglycosides.
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MacGregor RR, Dreyer K, Herman S, Hocknell PK, Nghiem L, Tevere VJ, Williams AL. Use of PCR in detection of Mycobacterium avium complex (MAC) bacteremia: sensitivity of the assay and effect of treatment for MAC infection on concentrations of human immunodeficiency virus in plasma. J Clin Microbiol 1999; 37:90-4. [PMID: 9854069 PMCID: PMC84175 DOI: 10.1128/jcm.37.1.90-94.1999] [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: 11/20/2022] Open
Abstract
We evaluated the sensitivity and specificity of a PCR-based qualitative test for the rapid diagnosis of Mycobacterium avium-M. intracellulare complex (MAC) bacteremia in patients with AIDS disease. Eleven subjects with newly culture-proven MAC bacteremia had the following tests performed at biweekly intervals during the first 8 weeks of therapy: blood culture, Mycobacterium-specific PCR, and quantitative human immunodeficiency virus (HIV) viral-load testing. Mycobacterium genus-specific biotinylated primers were used to amplify a sequence of approximately 582 nucleotides within the 16S rRNA genes of M. avium and M. intracellulare. Detection of the amplified product was performed with an oligonucleotide probe-coated microwell plate combined with an avidin-horseradish peroxidase-tetramethylbenzidine conjugate-substrate system. While not as sensitive as BACTEC culture, PCR detected 17 of 18 specimens which grew >/=40 organisms/ml (94.4% sensitivity) and 9 of 16 specimens which grew </=40 organisms/ml (56.3% sensitivity). No clear change in HIV viremia occurred in response to successful treatment of patients' MAC bacteremia. Use of the PCR test allowed detection of MAC bacteremia in 1 day, with a sensitivity similar to those of quantitative blood culture techniques, and it may prove useful for rapid screening of suspected cases. HIV viremia was unaffected by 8 weeks of MAC therapy.
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Williams AL, Gallup P. New admission measure needed. ACADEMIC MEDICINE : JOURNAL OF THE ASSOCIATION OF AMERICAN MEDICAL COLLEGES 1997; 72:159. [PMID: 9075413 DOI: 10.1097/00001888-199703000-00001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Mackert JR, Williams AL. Microcracks in dental porcelain and their behavior during multiple firing. J Dent Res 1996; 75:1484-90. [PMID: 8876600 DOI: 10.1177/00220345960750070801] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Dental porcelains rely on the high-thermal-expansion mineral leucite to elevate their bulk thermal expansion to levels compatible with dental PFM alloys. The microcracks that form around these leucite particles when cooled during porcelain manufacture are a potential source of change in bulk porcelain thermal expansion during fabrication of porcelain-fused-to-metal crowns and bridges. The purpose of the present study was to determine whether multiple firings of commercial dental porcelains could produce changes in microcrack density. Specimens of six commercial porcelains and the "Component No. 1" of the Weinstein patent were fabricated and subjected to 1, 2, 4, 8, and 16 firings. The microcrack densities were determined by quantitative stereology, whereby intersections of microcracks were counted with a test grid. The microcrack data were subjected to linear regression analysis and analysis of variance. The microcrack densities of four of the six porcelains and the Component No. 1 frit were not significantly affected by the number of firings (p > 0.05). One porcelain exhibited a weak but highly significant positive correlation between microcrack density and multiple firings (r2 = 0.24, p = 0.0003), while the remaining porcelain exhibited a weak but statistically significant negative correlation between microcrack density and multiple firings (r2 = 0.15, p = 0.006). The results of this study indicate that even for porcelains that exhibit a measurable change in microcrack density as a function of multiple firings, the magnitude of the increase or decrease in microcrack density after several firings is sufficiently small to cause only negligible shifts in porcelain bulk thermal expansion.
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Mackert JR, Khajotia SS, Russell CM, Williams AL. Potential interference of leucite crystallization during porcelain thermal expansion measurement. Dent Mater 1996; 12:8-12. [PMID: 8598254 DOI: 10.1016/s0109-5641(96)80057-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVES The elevated temperatures and slow heating and cooling rates associated with a thermal expansion run provide a thermal treatment comparable to those previously shown to produce leucite crystallization in dental PFM porcelains. The purpose of this study was to determine whether the exposure of dental porcelains to the time-temperature profile of a thermal expansion run could result in leucite crystallization, a potential interference with the accurate determination of the thermal expansion coefficient. METHODS A total of 112 thermal expansion specimens were prepared, 16 each of six commercially available body porcelains, as well as the "Component No. 1" (leucite-containing) frit of the Weinstein et al. (1962) patent. In a randomized design, the leucite contents of specimens subjected to a 3 degrees C/min thermal expansion run were compared to those of untreated controls. The leucite content of each specimen was determined via quantitative X-ray powder diffraction using an Al2O3 internal standard. One-tailed t-tests were applied to determine whether the dilatometer thermal treatment produced a statistically significant increase in leucite content. RESULTS The heat treatment afforded by a 3 degrees C/min dilatometer run was not sufficient to induce measurable leucite crystallization in any of the porcelains examined in this study. SIGNIFICANCE The crystallization of leucite during a dilatometer heating run can be ruled out as a possible interference with the determination of the coefficient of thermal expansion of dental porcelain.
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Sharafuddin MJ, Diemer DP, Levine RS, Thomasson JL, Williams AL. A comparison of MR sequences for lesions of the parotid gland. AJNR Am J Neuroradiol 1995; 16:1895-902. [PMID: 8693992 PMCID: PMC8338208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
PURPOSE To compare six MR sequences (plain and gadolinium-enhanced fat suppressed T1-weighted spin echo, T2-weighted standard spin echo, fat-suppressed and non-fat-suppressed T2-weighted fast spin echo, and inversion-recovery T2-weighted fast spin echo) in their ability to detect, delineate, and characterize lesions of the parotid gland. METHODS Fifty-eight parotid gland lesions imaged on 47 examinations were retrospectively evaluated by three blinded observers. Several outcome-related variables were compared by the above six sequences: imaging time, image quality, anatomic sharpness of parotid space, subjective lesion conspicuity, detected abnormality volume, number of individual lesions or discrete lobulations, conspicuity of invasion into adjacent boundaries and structures, and overall diagnostic value. RESULTS Differences in the above outcome variables between sequences did not correlate with MR scanner software upgrade level, coil type, or lesion-dependent characteristics. Fat-suppressed fast spin-echo T2-weighted and inversion-recovery fast spin-echo T2-weighted sequences resulted in significantly higher scores for lesion conspicuity, detected abnormality volume, and overall diagnostic value. T1-weighted images resulted in the next highest scores, whereas gadolinium-enhanced T1-weighted and standard spin-echo T2-weighted sequences performed poorly for most parotid lesions. CONCLUSION MR imaging of the parotid gland should include fat-suppressed, long-repetition-time, fast spin-echo T2-weighted, and T1-weighted sequences. Gadolinium-enhanced images need not be obtained routinely.
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Williams AL, Alford WP, Brash E, Brown BA, Burzynski S, Fortune HT, Häusser O, Helmer R, Henderson R, Hui PP, Jackson KP, Larson B, McKinzie MG, Smith DA, Trudel A, Vetterli M. Gamow-Teller strength in 60,62,64Ni(n,p) reactions at 198 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1995; 51:1144-1153. [PMID: 9970164 DOI: 10.1103/physrevc.51.1144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Fortune HT, Williams AL. Isospin dependence of double analog cross sections at T pi =400-500 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1994; 50:2927-2929. [PMID: 9969993 DOI: 10.1103/physrevc.50.2927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Williams AL. Health care reform and rationing: process lessons from the states. CLINICAL LABORATORY SCIENCE : JOURNAL OF THE AMERICAN SOCIETY FOR MEDICAL TECHNOLOGY 1994; 7:136-43. [PMID: 10147216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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McKinzie MG, Fortune HT, Hui P, Ivie R, Laymon C, Li X, Loe S, Smith DA, Williams AL, O'Donnell JM, Blanchard S, Burleson GR, Lail B. Interference effects in non-analog pion double charge exchange. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1994; 49:2054-2057. [PMID: 9969437 DOI: 10.1103/physrevc.49.2054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Rawool-Sullivan MW, Morris CL, O'Donnell JM, Whitton RM, Park BK, Burleson GR, Watson DL, Johnson J, Williams AL, Smith DA, Ernst DJ, Chen CM. Pion elastic scattering on 28Si at T pi =400 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1994; 49:627-629. [PMID: 9969266 DOI: 10.1103/physrevc.49.627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Wise JE, Braunstein MR, Hoibråten S, Kohler MD, Kriss BJ, Ouyang J, Peterson RJ, McGill JA, Morris CL, Seestrom SJ, Whitton RM, Zumbro JD, Edwards CM, Williams AL. Quasifree pion scattering at 500 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1993; 48:1840-1848. [PMID: 9969027 DOI: 10.1103/physrevc.48.1840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Zumbro JD, Morris CL, McGill JA, Seestrom SJ, Whitton RM, Edwards CM, Williams AL, Braunstein MR, Kohler MD, Kriss BJ, Hoibråten S, Peterson RJ, Ouyang J, Wise JE, Gibbs WR. Inclusive scattering of 500-MeV pions from carbon. PHYSICAL REVIEW LETTERS 1993; 71:1796-1799. [PMID: 10054502 DOI: 10.1103/physrevlett.71.1796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Beatty DP, Burleson GR, Rawool-Sullivan M, El-Ghossain M, Fortune HT, Williams AL, Smith DA, Morris CL, Garnett R, Watson DL, Johnson J, Ward H, Whitley C, Matthews SK, Palarczyk M, Edwards C, Espy M, Hashimoto O, Tomoyuki H. Pion double charge exchange on 16O at T pi =300-500 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1993; 48:1428-1430. [PMID: 9968973 DOI: 10.1103/physrevc.48.1428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Johnson JD, Burleson GR, Edwards C, El-Ghossain M, Espy MA, Garnett R, Hussein A, Johnson K, Moore CF, Morris CL, O'Donnell JM, Palarczyk M, Rawool-Sullivan M, Ward H, Watson D, Whitley C, Williams AL. Search for an eta bound state in pion double charge exchange on 18O. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1993; 47:2571-2573. [PMID: 9968730 DOI: 10.1103/physrevc.47.2571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Williams AL. Meet the matrix: information technology for clinical laboratory scientists. CLINICAL LABORATORY SCIENCE : JOURNAL OF THE AMERICAN SOCIETY FOR MEDICAL TECHNOLOGY 1993; 6:134-9. [PMID: 10146214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Kagarlis MA, Fortune HT, Hui P, Loe S, Smith DA, Williams AL, Urbina J. Double charge exchange in 93Nb( pi +, pi -)93Tc at T pi =164, 230, and 294 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1993; 47:1219-1224. [PMID: 9968554 DOI: 10.1103/physrevc.47.1219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Williams AL. The use of single-subject designs in clinical practice. CLINICS IN COMMUNICATION DISORDERS 1993; 3:47-58. [PMID: 8220384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Mark LP, Daniels DL, Naidich TP, Williams AL. Hippocampal anatomy and pathologic alterations on conventional MR images. AJNR Am J Neuroradiol 1993; 14:1237-40. [PMID: 8237709 PMCID: PMC8332759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Prestrelski SJ, Williams AL, Liebman MN. Generation of a substructure library for the description and classification of protein secondary structure. I. Overview of the methods and results. Proteins 1992; 14:430-9. [PMID: 1438181 DOI: 10.1002/prot.340140404] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Protein secondary structure has been typically classified into four major classes--alpha-helices, extended strands, reverse turns, and loops. Available methods for secondary structure analysis utilize predefined structure templates to search for structural matches among proteins. By this approach a significant portion of a proteins backbone conformation is assigned to one of a limited number of conformations or, if unassigned, to random coil. To expand our ability to describe protein secondary structure, we have developed an algorithm that operates independently of a predefined structure template. The procedure uses two geometric descriptors, the linear distance and the backbone dihedral angle, to represent the conformation form the alpha-carbon coordinates. The algorithm functions by searching for conformationally equivalent, contiguous fragments without regard to secondary structural classification and is thus independent of the complexity of the backbone fold. The result is a library of conformationally equivalent structure fragments that exhibit some novel characteristics. The library contains features that reproduce the major secondary structure classes as well as defining conformations previously described only as random or undefined conformations. Additionally, the library defines several subclassifications of beta-strands. We present here a validation of this method and a presentation and discussion of the most significant results. In a second study, we report the results of application of this method to spectra-structure correlations in Fourier transform infrared spectroscopy.
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Hendrix LE, Strandt JA, Daniels DL, Mark LP, Borne JA, Czervionke LF, Haughton VM, Williams AL. Three-dimensional time-of-flight MR angiography with a surface coil: evaluation in 12 subjects. AJR Am J Roentgenol 1992; 159:103-6. [PMID: 1609681 DOI: 10.2214/ajr.159.1.1609681] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We compared three-dimensional time-of-flight MR angiograms obtained with head coils and then with surface coils in five patients with intracranial vascular lesions and in seven normal volunteers to determine if imaging of intracranial vascular anatomy could be improved with the use of a surface coil. Visualization of small peripheral vessels was consistently better with a surface coil than with a head coil at identical small fields of view (FOVs). The surface-coil technique allowed small-FOV imaging of peripheral vascular lesions with higher spatial resolution and signal-to-noise ratio similar to that of large-FOV head-coil images. The use of a surface coil introduced the problem of signal falloff; centrally located vessels were visualized as well or better when a standard head coil was used. We conclude that surface-coil MR angiography can serve as a useful adjunct to routine head-coil MR angiography in the evaluation of peripheral vascular abnormalities.
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Jones MK, Dehnhard D, Nanda SK, Sterbenz SM, Morris CL, Plum M, Zumbro JD, Hussein AH, Oakley DS, Smithson MJ, Williams AL, McDonald J, Bryan MA, Fuentes AH, Lynker M, Crockett D, Machuca MA, Mordechai S, Moore CF. He4( pi, pi 'p)H3 reaction near the P33 pi -nucleon resonance. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1992; 46:52-63. [PMID: 9968086 DOI: 10.1103/physrevc.46.52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Oakley DS, Peterson RJ, Seestrom SJ, Morris CL, Plum MA, Zumbro JD, Williams AL, Bryan MA, McDonald JW, Moore CF. Energy dependence of pion inelastic scattering from 208Pb. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1991; 44:2058-2064. [PMID: 9967629 DOI: 10.1103/physrevc.44.2058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Abstract
This study reports the results of questioning 1,253 women about experiences of sexual abuse during childhood. An incidence of 3.5% was identified; many of those affected reported benefit from the opportunity to discuss what had happened, an aspect which should be facilitated during routine consultations. The study identified a substantial burden on emotional health presenting into adult life. The wide range of places where abuse occurred and of relationships between the abusers/victims has important implications for educating children.
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Williams AL, Johnson KW, Kahrimanis GP, Ward H, Moore CF, McGill JA, Morris CL, Burleson GR, Faucett JA, Rawool-Sullivan M, Oakley DS, Burlein M, Fortune HT, Insko E, Ivie R, O'Donnell JM, Smith D. Mass dependence of high-energy pion double charge exchange. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1991; 44:2025-2030. [PMID: 9967625 DOI: 10.1103/physrevc.44.2025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Watson DL, Gilman R, Morris CL, Zumbro JD, Mordechai S, Burlein M, O'Donnell JM, Fortune HT, Kotwal A, Puttz J, Silk JD, McDonald JS, Moore CF, Williams AL, Yoo SY. Pion-induced double charge exchange on 12C, 24Mg, 32S, and 40Ca. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1991; 43:1318-1320. [PMID: 9967171 DOI: 10.1103/physrevc.43.1318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Williams AL, McGill JA, Morris CL, Burleson GR, Faucett JA, Oakley DS, Burlein M, Fortune HT, O'Donnell JM, Kahrimanis GP, Moore CF. Pion double charge exchange on 42,44,48Ca for 300 <= T pi <= 550 MeV. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1991; 43:766-770. [PMID: 9967117 DOI: 10.1103/physrevc.43.766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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82
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Mark LP, Haughton VM, Hendrix LE, Daniels DL, Williams AL, Czervionke LF, Asleson RJ. High-intensity signals within the posterior pituitary fossa: a study with fat-suppression MR techniques. AJNR Am J Neuroradiol 1991; 12:529-32. [PMID: 2058509 PMCID: PMC8333009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Five different theories have been proposed to explain the high-intensity signals within the posterior pituitary fossa seen on MR: (1) a paramagnetic effect of phospholipids in the posterior lobe, (2) lipid in pituicytes in the posterior lobe of the pituitary, (3) neurosecretory granules in the posterior lobe, (4) fat within the sella but outside the pituitary gland, and (5) fat in bone marrow in the dorsum sellae. Previous reports have contained conflicting evidence on which of these structures is the cause of the high-intensity signals within the posterior sella. The purpose of this study was to examine the high-intensity signals of the normal posterior sella with fat-suppression MR techniques to reevaluate the contribution of fat to those signals. The sellae of 19 normal volunteers and two cadavers were imaged with MR with a commercially available unit and a research fat- water-suppression technique. High-intensity signals in the posterior sella were observed in all 21 subjects on conventional T1-weighted MR images. In two volunteers, the high-intensity signals in the posterior sella were suppressed with fat-suppression techniques; in 17 subjects the signals were suppressed with water-suppression techniques. In two volunteers the results were indeterminate. The high-intensity signals in the posterior sella do not behave like lipid in the majority of cases. Our study supports the conclusion that high-intensity signals in the posterior sella may have more than one source. It appears that most of these sources do not suppress with fat-suppression techniques.
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83
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Hendrix LE, Kneeland JB, Haughton VM, Daniels DL, Szumowski J, Williams AL, Mark LP, Czervionke LF. MR imaging of optic nerve lesions: value of gadopentetate dimeglumine and fat-suppression technique. AJR Am J Roentgenol 1990; 155:849-54. [PMID: 2119121 DOI: 10.2214/ajr.155.4.2119121] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Eleven patients with known or suspected optic nerve lesions and eight normal subjects were examined with spin-echo technique at 1.5 T with unenhanced T1-weighted imaging, IV gadopentetate-dimeglumine-enhanced T1-weighted imaging, and enhanced T1-weighted imaging with fat suppression. Two pathologically proved and four presumed optic nerve meningiomas demonstrated significant enhancement and were best seen with the fat-suppression technique. None of the three presumed optic nerve gliomas nor the optic nerves of normal subjects demonstrated qualitative enhancement. We conclude that the use of a fat-suppression technique with gadopentetate dimeglumine enhancement improves delineation of enhancing optic nerve lesions. This technique should be useful for evaluating other anatomic regions where enhancing tissue marginates fat.
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84
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Jones MK, Dehnhard D, Nanda SK, Sterbenz SM, Morris CL, Plum M, Zumbro JD, Hussein A, Oakley DS, Smithson MJ, Williams AL, McDonald J, Bryan MA, Fuentes AH, Lynker M, Crockett D, Machuca MA, Mordechai S, Moore CF. 4He( pi, pi 'p)3H reaction: Quasifree and resonance scattering. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1990; 42:807-810. [PMID: 9966790 DOI: 10.1103/physrevc.42.r807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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85
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86
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87
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Hendrix LE, Kneeland JB, Haughton VM, Daniels DL, Szumowski J, Williams AL, Mark LP, Czervionke LF. MR imaging of optic nerve lesions: value of gadopentetate dimeglumine and fat-suppression technique. AJNR Am J Neuroradiol 1990; 11:749-54. [PMID: 2114763 PMCID: PMC8331640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Eleven patients with known or suspected optic nerve lesions and eight normal subjects were examined with spin-echo technique at 1.5 T with unenhanced T1-weighted imaging, IV gadopentetate-dimeglumine-enhanced T1-weighted imaging, and enhanced T1-weighted imaging with fat suppression. Two pathologically proved and four presumed optic nerve meningiomas demonstrated significant enhancement and were best seen with the fat-suppression technique. None of the three presumed optic nerve gliomas nor the optic nerves of normal subjects demonstrated qualitative enhancement. We conclude that the use of a fat-suppression technique with gadopentetate dimeglumine enhancement improves delineation of enhancing optic nerve lesions. This technique should be useful for evaluating other anatomic regions where enhancing tissue marginates fat.
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88
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Breger RK, Williams AL, Daniels DL, Czervionke LF, Mark LP, Haughton VM, Papke RA, Coffer M. Contrast enhancement in spinal MR imaging. AJR Am J Roentgenol 1989; 153:387-91. [PMID: 2750625 DOI: 10.2214/ajr.153.2.387] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We evaluated 44 patients with suspected spinal tumors or previous laminectomies with gadolinium-DTPA MR imaging in order to characterize the enhancement in normal, postoperative, and neoplastic intraspinal tissue. Using the signal intensity of CSF as an internal control, we calculated the percentage increase in signal intensity from pre- to postgadolinium studies. Tumors (astrocytoma, ependymoma, schwannoma) enhanced 70-350%; epidural scar, normal epidural venous plexus, and dorsal root ganglion enhanced up to 200%. Contrast enhancement does not per se distinguish neoplastic from normal tissue. Enhancement with gadolinium-DTPA appeared to increase the conspicuousness of intramedullary tumors but not intraosseous metastases. We believe that gadolinium-enhanced MR imaging is a valuable adjunct to routine MR imaging in the evaluation of intraspinal neoplastic processes and may be useful in delineating normal and postoperative structures in the spinal canal.
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89
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Daniels DL, Czervionke LF, Millen SJ, Haberkamp TJ, Meyer GA, Hendrix LE, Mark LP, Williams AL, Haughton VM. MR imaging of facial nerve enhancement in Bell palsy or after temporal bone surgery. Radiology 1989; 171:807-9. [PMID: 2717756 DOI: 10.1148/radiology.171.3.2717756] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The authors evaluated magnetic resonance (MR) images obtained with intravenously administered gadolinium in ten patients who had facial paralysis and no facial nerve tumor. In patients with either Bell palsy (four patients) or facial paralysis after temporal bone surgery (six patients), intratemporal facial nerve enhancement was seen. Facial nerve enhancement on MR images proved to be a nonspecific finding.
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90
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Daniels DL, Czervionke LF, Hendrix LE, Mark LP, Smith DF, Meyer GA, Maiman DJ, Haughton VM, Williams AL. Gradient recalled echo MR imaging of superior sagittal sinus occlusion. Neuroradiology 1989; 31:134-6. [PMID: 2747889 DOI: 10.1007/bf00698840] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
With T1-weighted gradient recalled echo (GRE) MR images and flow compensation, we studied the superior sagittal sinus in 3 normal volunteers and 3 patients with sinus occlusion. In these images, sites of patency of the superior sagittal sinus were identified due to the high signal intensity of the normal sinus. Tumor invading the sinus was nearly isointense with cerebral gray matter. T1-weighted GRE imaging proves to be an effective technique to evaluate sinus blood flow.
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91
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Oakley DS, Peterson RJ, Rilett DJ, Morris CL, Greene SJ, Boyer B, Johnson K, Fuentes AH, McDonald JW, Smithson MJ, Williams AL, Yoo SH, Moore CF. Energy dependence of pion inelastic scattering to the 1(+) states in 12C. PHYSICAL REVIEW. C, NUCLEAR PHYSICS 1988; 38:2978-2981. [PMID: 9955149 DOI: 10.1103/physrevc.38.2978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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92
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Czervionke LF, Daniels DL, Ho PS, Yu SW, Pech P, Strandt J, Williams AL, Haughton VM. Cervical neural foramina: correlative anatomic and MR imaging study. Radiology 1988; 169:753-9. [PMID: 3186997 DOI: 10.1148/radiology.169.3.3186997] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Accurate diagnosis of diseases affecting the cervical neural foramina with magnetic resonance (MR) imaging requires an appreciation of the normal anatomic appearance of the foramen. The MR appearance of the foramen was studied in cadavers and healthy volunteers and was correlated with cadaver cryomicrotome sections. With gradient-echo techniques, foraminal soft tissues are highlighted relative to adjacent bone, making gradient-echo images valuable for evaluating the overall size and contents of the neural foramina. Intravenously administered gadolinium DTPA produces enhancement of all foraminal soft tissues, including the dorsal root ganglion. The nerve roots do not enhance with Gd-DTPA. Gradient-echo pulse sequences and intravenous use of Gd-DTPA represent promising techniques for the evaluation of the cervical foramina.
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Abstract
Among steps to improve immunisation rates in Clwyd an advisory service was introduced for children with immunisation problems. We report on setting up the service and the first two years of running it; during this time 191 children attended. Influencing parental and professional attitudes through education, counselling, and the demonstration of good practice is emphasised.
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Daniels DL, Czervionke LF, Bonneville JF, Cattin F, Mark LP, Pech P, Hendrix LE, Smith DF, Haughton VM, Williams AL. MR imaging of the cavernous sinus: value of spin echo and gradient recalled echo images. AJR Am J Roentgenol 1988; 151:1009-14. [PMID: 3262998 DOI: 10.2214/ajr.151.5.1009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A detailed evaluation of the MR appearance of the pituitary gland-cavernous sinus junction has not been described. In a series of coronal T1-weighted spin echo images without and with IV gadolinium, we noted the variable size and signal intensity of cavernous venous spaces adjacent to the pituitary gland and the inconsistent visualization of the dural membrane just lateral to the gland. Correlation of coronal T1-weighted spin echo and gradient recalled echo images (the latter with high-signal-intensity vascular structures) proved to be an effective means of identifying cavernous venous spaces, connective tissue and cranial nerves, and the lateral margins of the pituitary gland, and of differentiating tumor tissue from cavernous venous spaces. Further work is needed to develop criteria to distinguish cavernous sinus compression from actual tumor invasion.
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95
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Daniels DL, Czervionke LF, Yu S, Ho PS, Pech P, Pojunas KW, Williams AL, Haughton VM. The effect of patient positioning on MR imaging of the internal auditory canal. Neuroradiology 1988; 30:395-8. [PMID: 3211315 DOI: 10.1007/bf00404104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Identification of individual cranial nerves and complete exclusion of tumor in the internal auditory canal may be difficult with MR, especially in imperfectly positioned patients. MR studies of the temporal bones in patients and in normal volunteers positioned non-rotated or canted were correlated with corresponding cryomicrotomic sections. Especially in axial images, oblique sectioning of cranial nerves VII and VIII may cause difficulty in identifying individual nerves. A combination of axial and coronal short TR and TE images can be used to confidently exclude intracanalicular tumor in most cases.
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96
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Williams AL, Hoofnagle JH. Ratio of serum aspartate to alanine aminotransferase in chronic hepatitis. Relationship to cirrhosis. Gastroenterology 1988; 95:734-9. [PMID: 3135226 DOI: 10.1016/s0016-5085(88)80022-2] [Citation(s) in RCA: 311] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The ratio of the serum aspartate to alanine amino-transferase levels (AST/ALT) is often used as a clue to the etiology of the underlying liver disease. This ratio is usually greater than 2.0 in alcoholic liver disease and less than 1.0 in patients with chronic hepatitis and chronic cholestatic syndromes. We analyzed the AST/ALT ratio in 177 patients with various forms of nonalcoholic chronic liver disease who underwent medical evaluation and percutaneous liver biopsy. In the majority of cases of chronic viral hepatitis, the AST/ALT ratio was less than 1.0. However, there was a statistically significant correlation between the AST/ALT ratio and the presence of cirrhosis. Among 100 patients with chronic type B hepatitis, the mean AST/ALT ratio was 0.59 in those without cirrhosis and 1.02 in those with cirrhosis. Furthermore, the AST/ALT ratio often rose to greater than 1.0 when cirrhosis first became manifest. Thus, the finding of an AST/ALT ratio of greater than 1.0 in a patient with nonalcoholic liver disease should suggest the presence of cirrhosis. In addition, the use of the AST/ALT ratio as a means of separating alcoholic and nonalcoholic liver disease must be tempered with the knowledge that this ratio may be less helpful in the presence of cirrhosis.
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97
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Haughton VM, Rimm AA, Czervionke LF, Breger RK, Fisher ME, Papke RA, Hendrix LE, Strother CM, Turski PA, Williams AL. Sensitivity of Gd-DTPA-enhanced MR imaging of benign extraaxial tumors. Radiology 1988; 166:829-33. [PMID: 3340779 DOI: 10.1148/radiology.166.3.3340779] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The effect of gadolinium diethylenetriaminepentaacetic acid (DTPA) on the sensitivity of cranial magnetic resonance (MR) imaging was measured in a prospective blinded study. Twenty-two consecutive patients with benign extraaxial tumors underwent MR imaging on a 1.5-T system without and with intravenous administration of Gd-DTPA. Readers independently interpreted the unenhanced and enhanced images without clinical information. The interpretations were compared with the anatomically verified diagnoses. Gd-DTPA improved the sensitivity of MR imaging for benign extraaxial tumors, especially in cases of residual or recurrent acoustic neuromas, multiple tumors (e.g., neurofibromatosis), or inconclusive unenhanced MR images. Enhancement with Gd-DTPA impaired the identification of a skull base tumor.
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98
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Czervionke LF, Daniels DL, Ho PS, Yu SW, Pech P, Strandt JA, Williams AL, Haughton VM. The MR appearance of gray and white matter in the cervical spinal cord. AJNR Am J Neuroradiol 1988; 9:557-62. [PMID: 3132831 PMCID: PMC8332793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Artifacts that can distort the appearance of the cervical spinal cord are caused by data truncation during MR image reconstruction. We used a phantom and then correlated anatomic sections with MR images in cadavers and normal volunteers to evaluate the effect of truncation artifacts on the MR appearance of the spinal cord. When truncation artifacts are minimized, the gray matter and major white-matter columns in the cervical cord can be recognized. T2-weighted gradient-echo MR techniques can best differentiate gray from white matter.
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99
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Daniels DL, Czervionke LF, Pech P, Hendrix LE, Mark LP, Smith DF, Haughton VM, Williams AL. Gradient recalled echo MR imaging of the jugular foramen. AJNR Am J Neuroradiol 1988; 9:675-8. [PMID: 3135713 PMCID: PMC8332021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Axial T1-weighted spin-echo MR images have not proved to be effective in identifying normal structures in the jugular foramen. By correlating cryomicrotomic sections and axial T1-weighted gradient recalled echo images, we identified the neural and vascular contents of the jugular foramen. Further work with gradient recalled echo images is needed to determine the signal characteristics of jugular foraminal lesions.
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100
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Czervionke LF, Daniels DL, Wehrli FW, Mark LP, Hendrix LE, Strandt JA, Williams AL, Haughton VM. Magnetic susceptibility artifacts in gradient-recalled echo MR imaging. AJNR Am J Neuroradiol 1988; 9:1149-55. [PMID: 3143237 PMCID: PMC8331920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Artifacts related to magnetic susceptibility differences between bone and soft tissue are prevalent on gradient-recalled echo images, particularly when long echo delay times are used. These susceptibility artifacts spatially distort and artifactually enlarge bone contours. This can alter the apparent shape of the spinal canal and exaggerate the degree of spinal stenosis seen in patients with cervical spondylosis. The effects of magnetic susceptibility artifacts in gradient echo imaging were studied in a phantom model and the results were correlated with MR images obtained in patients with cervical spondylosis.
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