101
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Cramer JA, Bennett DM, Mattson RH. Free and bound valproic acid separated by two methods of ultrafiltration. Clin Chem 1983. [DOI: 10.1093/clinchem/29.7.1441] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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102
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Cramer JA, McCarthy KA, Mattson RH. Free fraction of valproic acid is the same in serum and plasma. Clin Chem 1983. [DOI: 10.1093/clinchem/29.7.1449] [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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103
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Cramer JA, Smith DB, Mattson RH, Delgado Escueta AV, Collins JF. A method of quantification for the evaluation of antiepileptic drug therapy. Neurology 1983; 33:26-37. [PMID: 6681889 DOI: 10.1212/wnl.33.3_suppl_1.26] [Citation(s) in RCA: 115] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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104
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Mattson RH, Cramer JA, Delgado Escueta AV, Smith DB, Collins JF. A design for the prospective evaluation of the efficacy and toxicity of antiepileptic drugs in adults. Neurology 1983; 33:14-25. [PMID: 6681888 DOI: 10.1212/wnl.33.3_suppl_1.14] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The design for the comparative evaluation of the efficacy and toxicity of phenobarbital, phenytoin, primidone, and carbamazepine is outlined. A double-blind prospective study of a sufficient number of patients can determine the optimum drug to use initially for partial and generalized tonic-clonic seizures in adults. The rationale for methods defines the major parameters that should be addressed in order to determine optimum drug for longterm seizure therapy. Major problems in the function of such a project include aspects of sample size attainment, screening/recruitment, non-drug-related losses, and adjustments to the ongoing protocol. The design, with modifications, can be used to study other antiepileptic drugs and other types of seizures.
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105
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Smith DB, Delgado Escueta AV, Cramer JA, Mattson RH. Historical perspective on the choice of antiepileptic drugs for the treatment of seizures in adults. Neurology 1983; 33:2-7. [PMID: 6338417 DOI: 10.1212/wnl.33.3_suppl_1.2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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106
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Delgado Escueta AV, Mattson RH, Smith DB, Cramer JA, Collins JF. Principles in designing clinical trials for antiepileptic drugs. Neurology 1983; 33:8-13. [PMID: 6681890 DOI: 10.1212/wnl.33.3_suppl_1.8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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107
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Mattson GF, Mattson RH, Cramer JA. Interaction between valproic acid and carbamazepine: an in vitro study of protein binding. Ther Drug Monit 1982; 4:181-4. [PMID: 6808714 DOI: 10.1097/00007691-198206000-00004] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Valproic acid (VPA) is highly bound to plasma protein (92-96%) and is likely to compete with carbamazepine (CBZ), another drug that is bound extensively (75%). CBZ protein binding was evaluated in vitro by ultrafiltration at concentrations within the therapeutic range (6, 8, and 12 micrograms/ml), while also varying VPA concentrations (0, 50, and 100 micrograms/ml). Using ultrafiltration, we found a significant elevation (p less than 0.01) in free and percent-free CBZ for every CBZ concentration tested as the total VPA concentration increased. Maximal effect was evident at 12 micrograms/ml CBZ. The free fraction increased from 23.5% free CBZ controls (2.85% micrograms/ml free) to 29.5% free CBZ (3.56% micrograms/ml free), with 100 micrograms/ml VPA a 25% increase in free CBZ. This in vitro study demonstrates that VPA competes with CBZ for plasma protein binding sites, resulting in a significant increase in free CBZ that may be clinically important.
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109
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Abstract
The addition of valproic acid to ethosuximide in treatment to prevent seizures caused increased serum concentration of ethosuximide in four of five patients observed. Ethosuximide levels increased from 73 to 112 microgram/ml (53% higher), with concomitant toxicity. Both were reversed by reduction of the ethosuximide dose from 27.4 to 20.4 mg/kg. Serum concentrations of these two drugs should be monitored closely when they are given together.
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110
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Cramer JA, Marchesi VT, Armitage IM. Reversible trifluoroacetic acid-induced conformational changes in glycophorin A as detected by proton nuclear magnetic resonance spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 595:235-43. [PMID: 7352997 DOI: 10.1016/0005-2736(80)90086-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
High-field (270 MHz) 1H-NMR has been employed to study the solution conformation of glycophorin A, a sialoglycoprotein which spans the human erythrocyte membrane. Glycophorin A is one of the most fully characterized integral membrane proteins known, making it an excellent model for the study of membrane-bound proteins. This protein consists of three distinct domains: a glycosylated extracellular N-terminus, a hydrophobic intramembranous segment, and a polar cytoplasmic C-terminus. These domains contain aromatic residues which serve as convenient 1H-NMR conformational probes. The aromatic region of the NMR spectrum of glycophorin A in 2H2O shows single, well-resolved His and Tyr resonances. No resonances are observed, however, for the Phe residues which are located in or near the hydrophobic domain. These observations suggest that considerable heterogeneity with respect to segmental motions exists within the protein. This is consistent with circular dichroism data showing the intramembranous segment to be completely helical with the extremities of the protein being predominantly random coils. The helix of the hydrophrobic domain is remarkably resistant to conventional denaturing conditions including variations in pH, and temperature, and treatment with guanidine hydrochloride. However, in trifluoroacetic acid, which strongly solvates peptide backbones, there is extensive reversible unfolding of the helical structure as evidenced by the appearance of Phe resonances. Solvent titration experiments indicate that approximately a 1 : 1 volume ratio of trifluoroacetic acid to 2H2O is required to initiate unfolding of the helix.
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111
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Falsetti HL, Verani MS, Chen CJ, Cramer JA. Regional pressure differences in the left ventricle. CATHETERIZATION AND CARDIOVASCULAR DIAGNOSIS 1980; 6:123-34. [PMID: 7407900 DOI: 10.1002/ccd.1810060203] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Theoretically, if blood is to have directional flow and different magnitudes of velocity, pressure should be distributed in the left ventricle (LV) as a function of both space and time. Thus, regional pressure differences (RPD) were examined in the LV of 20 open-chested dogs. High-fidelity transducers were implanted through stab wounds at three positions in the LV: the base (B), equator (EQ), and apex (APX). Simultaneous, high-fidelity LV pressures were compared in each region under rest conditions and during graded infusions of isoproterenol and propranolol. In the baseline condition, there were slight but significant differences between the APX and B in end-diastolic pressure (EDP), peak systolic pressure (PSP), peak dp/dt and Vmax. At rest, the largest RPD between the APX and B in PSP was 9 mm Hg (mean +/- 1 SE = 2.1 +/- 0.5), and the largest during diastole was 5.1 mm Hg (mean +/- 1 SE = 1.2 +/- 0.4); the largest difference in Vmax was 30.5% (mean +/- 1 SE = 10.8 +/- 2.4). During isoproterenol infusion the RPD in PSP were accentuated; the largest seen was 84 mm Hg between APX and B (mean +/- 1 SE = 15.7 +/- 4.5). The largest difference in Vmax between B and APX was 188% (mean +/- 1 SE = 48.5 +/- 9.4). Propranolol obliterated these RPD. These results indicate that there are significant RPD in the LV cavity; during systole the highest pressures decrease sequentially from the apex to the equator and to the base; during diastole these RPD are of lesser magnitude. These RPD affect all derived pressure indices, and these changes can be increaed or decreased by drug intervention. These results are important for two reasons: 1) the position of catheters in the LV cavity is important when pressure-dependent LV parameters are compared in different conditions; and 2) in any force balance analysis of the left ventricle it is important to note that force generation by the left ventricle is an active process that transmits regional pressure differences to the LV cavity.
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112
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Falsetti HL, Verani MS, Cramer JA, Carroll R. Total, phasic, and regional myocardial blood flow in aortic stenosis. Am Heart J 1979; 98:331-8. [PMID: 474379 DOI: 10.1016/0002-8703(79)90045-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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113
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Prestegard JH, Cramer JA, Viscio DB. Nuclear magnetic resonance determinations of permeation coefficients for maleic acid in phospholipid vesicles. Biophys J 1979; 26:575-84. [PMID: 45401 PMCID: PMC1328571 DOI: 10.1016/s0006-3495(79)85272-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lipid bilayer permeation coefficients for the neutral maleic acid molecule and the maleate monoanion have been determined by proton magnetic resonance techniques. Phosphatiydylcholine-cholesterol (2:1) unilamellar vesicles were prepared having an initial maleate anion concentration gradient stabilized by coupling to an impermeant potassium counterion. The coupling was released by addition of valinomycin, and the time evolution of external pH, internal pH, and maleate concentration followed using nuclear magnetic resonance areas and chemical shifts. Transport rate equations were numerically integrated to fit the date, yielding best fit permeation coefficients of 4 X 10(-9) and 4 X 10(-5) cm/s for maleate monoanion and maleic acid, respectively.
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114
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115
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Mattson RH, Cramer JA, Williamson PD, Novelly RA. Valproic acid in epilepsy: clinical and pharmacological effects. Ann Neurol 1978; 3:20-5. [PMID: 350128 DOI: 10.1002/ana.410030105] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The antiepileptic drug valproic acid was studied in an open clinical trial as adjunct medication for 23 patients with uncontrolled seizures of a generalized or partial type. Two-thirds of the patients experienced reduction in seizure frequency ranging from 25 to 100%. Extensive testing revealed no evidence of serious systemic toxicity due to the drug. Minor side effects (e.g., nausea, vomiting, or sedation) were usually transient. Sodium valproate syrup and valproic acid in capsules gave equivalent mean low (23.3 microgram/ml) and maximum (42.5 microgram/ml) serum concentrations. The drug had a relatively short half-life of 8.7 hours, necessitating administration in divided daily doses. During initiation of valproate therapy there was evidence of a decline in total serum phenytoin concentration (16.5 to 10.2 microgram/ml; p less than 0.001) while the percentage of free phenytoin increased (10.9 to 20%). The quantity of unbound phenytoin was relatively stable throughout. This observation was interpreted as a drug interaction: valproic acid competed with phenytoin for access to plasma protein binding sites.
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116
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Cramer JA, Prestegard JH. NMR studies of pH-induced transport of carboxylic acids across phospholipid vesicle membranes. Biochem Biophys Res Commun 1977; 75:295-301. [PMID: 15562 DOI: 10.1016/0006-291x(77)91042-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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117
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Caride VJ, Taylor W, Cramer JA, Gottschalk A. Evaluation of liposome-entrapped radioactive tracers as scanning agents. Part 1: Organ distribution of liposome (99mTc-DTPA) in mice. J Nucl Med 1976; 17:1067-72. [PMID: 993839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We describe the use of liposomes as a delivery system for radiopharmaceutical localization. Liposomes [99mTc-DTPA] were injected intravenously in mice and showed preferential uptake in the liver and spleen. There was a steady decline of activity in all organs, suggestive of destruction of liposomes with subsequent release of 99mTc-DTPA into the circulation. Alteration of uptake from liver to spleen, lung, and bone marrow was achieved by prior loading of the circulation with nonradioactive liposomes. The same effect was produced in dogs and demonstrated with scintigraphy. We also showed scintigraphically in dogs how 99mTc-DTPA, when administered entrapped in liposomes, follows the pattern of distribution of liposomes. Liposomes seem to be suitable carriers for radiopharmaceuticals. Further studies should show the possibility of directing liposomes to specific targets.
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118
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Cohn GL, Cramer JA, McBride W, Brown RC, Kleber HD. Heroin and morphine binding with human serum proteins and red blood cells. PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE. SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE (NEW YORK, N.Y.) 1974; 147:664-6. [PMID: 4445151 DOI: 10.3181/00379727-147-38411] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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119
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Cohn GL, Cramer JA, Kleber HD. Heroin metabolism in the rat. PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE. SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE (NEW YORK, N.Y.) 1973; 144:351-5. [PMID: 4797806 DOI: 10.3181/00379727-144-37589] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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120
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Rinalducci EJ, Higgins KE, Cramer JA. Nonequivalence of backgrounds during photopic dark adaptation. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA 1970; 60:1518-24. [PMID: 5312329 DOI: 10.1364/josa.60.001518] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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121
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Steinberg GM, Cramer JA. (3-bromo-2-oxopropyl)trimethylammonium bromide, an inhibitor of acetylcholinesterase. Biochem Pharmacol 1970; 19:632-6. [PMID: 5507674 DOI: 10.1016/0006-2952(70)90224-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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