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  • Biochemistry and Biotechnology  (12)
  • Computational Chemistry and Molecular Modeling  (6)
  • pharmacokinetics  (5)
  • Biochemistry  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Risk analysis 19 (1999), S. 711-726 
    ISSN: 1539-6924
    Keywords: variability ; exposure ; susceptibility ; risk assessment ; pharmacokinetics ; pharmacodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper reviews existing data on the variability in parameters relevant for health risk analyses. We cover both exposure-related parameters and parameters related to individual susceptibility to toxicity. The toxicity/susceptibility data base under construction is part of a longer term research effort to lay the groundwork for quantitative distributional analyses of non-cancer toxic risks. These data are broken down into a variety of parameter types that encompass different portions of the pathway from external exposure to the production of biological responses. The discrete steps in this pathway, as we now conceive them, are: •Contact Rate (Breathing rates per body weight; fish consumption per body weight) •Uptake or Absorption as a Fraction of Intake or Contact Rate •General Systemic Availability Net of First Pass Elimination and Dilution via Distribution Volume (e.g., initial blood concentration per mg/kg of uptake) •Systemic Elimination (half life or clearance) •Active Site Concentration per Systemic Blood or Plasma Concentration •Physiological Parameter Change per Active Site Concentration (expressed as the dose required to make a given percentage change in different people, or the dose required to achieve some proportion of an individual's maximum response to the drug or toxicant) •Functional Reserve Capacity–Change in Baseline Physiological Parameter Needed to Produce a Biological Response or Pass a Criterion of Abnormal Function Comparison of the amounts of variability observed for the different parameter types suggests that appreciable variability is associated with the final step in the process–differences among people in “functional reserve capacity.” This has the implication that relevant information for estimating effective toxic susceptibility distributions may be gleaned by direct studies of the population distributions of key physiological parameters in people that are not exposed to the environmental and occupational toxicants that are thought to perturb those parameters. This is illustrated with some recent observations of the population distributions of Low Density Lipoprotein Cholesterol from the second and third National Health and Nutrition Examination Surveys.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Histamine ; Biochemistry ; Immunocytochemistry ; Retina ; Photoreceptors ; Paraboloid ; Turtle, Pseudemys scripta (Chelonia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A combination of immunocytochemical and biochemical methods was used to study histamine in the turtle retina. Histamine-like immunoreactivity was localized within paraboloids of certain cone photoreceptors by use of two different antisera directed against histamine. Preincubation of eyecups in Ringer's containing 10 μM histamine selectively increased the immunoreactivity of these photoreceptor paraboloids. The present localization of histamine in paraboloids indicated that, although histamine is in photoreceptors of the turtle retina, it may play some metabolic or neuromodulatory role, and not function as a neurotransmitter.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 11 (1994), S. 1204-1206 
    ISSN: 1573-904X
    Keywords: phenobarbital ; pharmacokinetics ; milk ; rabbit ; neonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pharmacokinetics and pharmacodynamics 7 (1979), S. 265-274 
    ISSN: 1573-8744
    Keywords: furosemide ; indomethacin ; prostaglandin ; pharmacokinetics ; pharma-codynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics and pharmacodynamics of intravenous furosemide, 40 mg, were studied in four normal males in a crossover fashion with and without indomethacin pretreatment. In each study 16 plasma and 10 urine samples were collected over 24 hr. Fluid and electrolyte urinary losses were replaced orally throughout the study. Unchanged furosemide and indomethacin were measured using HPLC; urinary sodium was measured by flame photometry. Pretreatment with indomethacin resulted in increased and prolonged furosemide plasma levels, increased area under the curve, decreased plasma clearance, decreased renal clearance, increased half-life, no change in volume of distribution, and decreased sodium excretion and urine volume. Analysis of sodium excretion rate with time shows that the inhibiting effect of indomethacin was greater during the first 2 hr than at later times.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pharmacokinetics and pharmacodynamics 11 (1983), S. 31-46 
    ISSN: 1573-8744
    Keywords: bumetanide ; probenedd ; pharmacokinetics ; pharmacodynamics ; doseresponse relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics and pharmacodynamics of intravenous bumetanide (0.250 mg/kg), alone (treatment I) and after probenecid pretreatment (treatment II), were studied in four mongrel dogs. Lactated Ringer's solution was administered by vein throughout both treatments at a flow rate of 2 ml/min to avoid fluid and electrolyte depletion. Bumetanide and probenecid concentrations were analyzed by HPLC, sodium by flame photometry, and creatinine by colorimetry. Although the probenecid markedly reduced the plasma and renal clearances of bumetanide, as well as the fraction excreted unchanged in the urine, there was no significant difference between treatments I and II in the 4-hr natriuretic and diuretic responses. However, analysis of the dose-response curves between treatments I and II showed that sodium, excretion was better correlated with bumetanide urinary excretion rate than with plasma concentration. The reasons for a poor correlation between treatments during the early time periods are discussed.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-904X
    Keywords: allometric scaling ; peptide ; pharmacokinetics ; hematology ; infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study the pharmacokinetics of SK&F 107647, a novel hematoregulatory agent, in rats, dogs, and patients with non-lymphoid solid tumor malignancy. Methods. Sprague Dawley rats and beagle dogs (n = 6 each; 3 M, 3 F) were given 25 mg/kg of SK&F 107467 as an iv bolus injection, and patients (n = 6; 4 M, 2 F) received 100 ng/kg as a 2 hour iv infusion. Plasma samples were assayed for drug using either HPLC (rat and dog) or RIA (human). Results. In each species the plasma clearance (CL) of SK&F 107647 was low in relation to hepatic blood flow, and the volume of distribution (Vdss) was reflective of distribution to extracellular body water. The plasma CL in humans was near that of average glomerular filtration rate. Using allometric equations for interspecies scaling (Y = a·Wb), body-weight normalized human pharmacokinetic data were reasonably predicted using either the body weight normalized rat or the dog data. The allometric exponents (b) for CL, Vdss, and T1/2 of SK&F 107647 were 0.63, 0.94, and 0.29, respectively. Conclusions. Use of a limited pool of available animal data allowed for reasonable predictions of human pharmacokinetics of SK&F 107647.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of gas-phase electron transfer reactions for a variety of metal-containing reactants have been studied by using Fourier transform ion cyclotron resonance mass spectrometry. Classes of ion/molecule processes studied include both self-exchange (thermoneutral) and exoergic cross reactions. The molecules investigated include metallocenes and octahedral coordination complexes of the transition elements. In a few cases, direct comparisons of condensed-phase and gas-phase reactivities can be made. The experiments with octahedral coordination complexes are the first studies of Werner-type metal complexes in electron-transfer reactions in the gas phase. Simple theoretical models involving unimolecular rate theory, classical reorganization barriers, and quantum mechanical approaches are used to rationalize the dependence of the overall rates of these reactions on the molecular properties of the reactants. In particular, the role of Franck-Condon factors in charge-transfer reactions is examined, and theoretically estimated factors are compared with experiment for a typical metallocene, ferrocene.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 18 (1994), S. 205-215 
    ISSN: 0887-3585
    Keywords: peptide folding ; disulfide framework ; insect toxins ; NMR ; distance geometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: An analysis of the sequences of scyllatoxin and charybdotoxin suggested that it would be possible to design a core peptide sequence which would still fold to give the β-hairpin and helix seen in the toxins, but which would eliminate one disulfide and connecting residues. The core sequence was modeled, then synthesized and purified. The cysteines oxidize in air to give the same disulfide pairings as seen in the parent toxins as the major product. The three-dimensional structure of the core sequence peptide, termed Max, was determined using proton NMR spectroscopy and found to be identical in secondary structure to the toxins. However differences were found in the relative orientation of the β-hairpin and helix. The use of this structural motif, found in many insect toxins, as a disulfide framework for exploring sequence/structure/activity relationships is discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 11 (1991), S. 142-152 
    ISSN: 0887-3585
    Keywords: AMBER ; electrostatics ; protein-protein interactions ; intermolecular bonding ; electron transfer ; redox proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Molecular dynamics simulations have been carried out on the complex formed between the tetraheme cytochrome c3 and the iron protein rubredoxin from the sulfate-reducing bacterium Desulfovibrio vulgaris. These simulations were performed both with explicit solvent water molecules included, and without solvent molecules using a distance-dependent dielectric constant to approximate the screening effects of solvent. The results of both simulations are strikingly different, indicating that the representation of environmental effects is important in such simulations. For example, a striking adaptation of the two proteins seen in the nonsolvated simulation is not seen when explicit solvent water is included; in fact, the complex appears to become weaker in the solvated simulation. Nonetheless, the iron-iron distance decreases more significantly in the solvated simulation than in the nonsolvated simulation. It was found that in both cases molecular dynamics optimized the structures further than energy minimization alone.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 16 (1993), S. 306-308 
    ISSN: 0887-3585
    Keywords: rubredoxin ; lgG antibody ; lgM antibody ; immunogen ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The immunogenicity of a folded, all D-amino acid protein- rubredoxin, has been compared with that for the corresponding L-protein enantiomer. Following multiple administrations with alum adjuvant, the L-protein induced a strong, specific lgG antibody response, whereas the D-protein did not. This relative lack of responsiveness to the D-protein cannot be attributed to rapid excretion, since it is retained at least 4 times longer than the natural L-protein. These observations provide the first direct evidence that a folded D-amino acid protein has low immunogenicity and is long lived in vivo. Proteins with such properties may be useful as molecular platforms in a variety of chemical and pharmaco-logical applications. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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