The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Thomas Deufel - One of the best experts on this subject based on the ideXlab platform.
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Strong interference of hemoglobin concentration on CSF total protein measurement using the Trichloroacetic Acid precipitation method
Clinical Chemistry and Laboratory Medicine, 2007Co-Authors: Klas Böer, Stefan Isenmann, Thomas DeufelAbstract:Background: Among other methods, Trichloroacetic Acid precipitation is used to quantify total protein in cerebrospinal fluid (CSF). Methods: We analyzed the influence of hemoglobin on total protein concentration assayed by the Trichloroacetic Acid method and compared the results to the benzethonium chloride method. Results: Four CSF samples were spiked with different amounts of hemoglobin, leading to overestimation of protein concentration when assayed by the Trichloroacetic Acid method. Using the benzethonium chloride method, measurement of protein concentration was minimally disturbed. In addition, albumin and total protein concentrations were measured in 135 clinical samples. The total protein/albumin ratio remained constant when protein was measured with the benzethonium chloride method, while ratios increased when protein was assayed by the Trichloroacetic Acid method. Conclusions: Strong interference by hemoglobin leads to overestimation of the total protein concentration in CSF when assayed by the Trichloroacetic Acid method and may lead to false conclusions when evaluating the blood-brain barrier.
Klas Böer - One of the best experts on this subject based on the ideXlab platform.
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Strong interference of hemoglobin concentration on CSF total protein measurement using the Trichloroacetic Acid precipitation method
Clinical Chemistry and Laboratory Medicine, 2007Co-Authors: Klas Böer, Stefan Isenmann, Thomas DeufelAbstract:Background: Among other methods, Trichloroacetic Acid precipitation is used to quantify total protein in cerebrospinal fluid (CSF). Methods: We analyzed the influence of hemoglobin on total protein concentration assayed by the Trichloroacetic Acid method and compared the results to the benzethonium chloride method. Results: Four CSF samples were spiked with different amounts of hemoglobin, leading to overestimation of protein concentration when assayed by the Trichloroacetic Acid method. Using the benzethonium chloride method, measurement of protein concentration was minimally disturbed. In addition, albumin and total protein concentrations were measured in 135 clinical samples. The total protein/albumin ratio remained constant when protein was measured with the benzethonium chloride method, while ratios increased when protein was assayed by the Trichloroacetic Acid method. Conclusions: Strong interference by hemoglobin leads to overestimation of the total protein concentration in CSF when assayed by the Trichloroacetic Acid method and may lead to false conclusions when evaluating the blood-brain barrier.
Richat Abbas - One of the best experts on this subject based on the ideXlab platform.
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A human physiologically based pharmacokinetic model for trichloroethylene and its metabolites, Trichloroacetic Acid and free trichloroethanol.
Toxicology and applied pharmacology, 1998Co-Authors: Jeffrey W. Fisher, Deirdre A. Mahle, Richat AbbasAbstract:Nine male and eight female healthy volunteers were exposed to 50 or 100 ppm trichloroethylene vapors for 4 h. Blood, urine, and exhaled breath samples were collected for development of a physiologically based pharmacokinetic (PBPK) model for trichloroethylene and its two major P450-mediated metabolites, Trichloroacetic Acid and free trichloroethanol. Blood and urine were analyzed for trichloroethylene, chloral hydrate, free trichloroethanol and trichloroethanol glucuronide, and Trichloroacetic Acid. Plasma was analyzed for dichloroacetic Acid. Trichloroethylene was also measured in exhaled breath samples. Trichloroethylene, free trichloroethanol, and Trichloroacetic Acid were found in blood samples of all volunteers and only trace amounts of dichloroacetic Acid (4–12 ppb) were found in plasma samples from a few volunteers. Trichloroethanol glucuronide and Trichloroacetic Acid were found in urine of all volunteers. No chloral hydrate was detected in the volunteers. Gender-specific PBPK models were developed with fitted urinary rate constant values for each individual trichloroethylene exposure to describe urinary excretion of trichloroethanol glucuronide and Trichloroacetic Acid. Individual urinary excretion rate constants were necessary to account for the variability in the measured cumulative amount of metabolites excreted in the urine. However, the average amount of Trichloroacetic Acid and trichloroethanol glucuronide excreted in urine for each gender was predicted using mean urinary excretion rate constant values for each sex. A four-compartment physiological flow model was used for the metabolites (lung, liver, kidney, and body) and a six-compartment physiological flow model was used for trichloroethylene (lung, liver, kidney, fat, and slowly and rapidly perfused tissues). Metabolic capacity (Vmaxc) for oxidation of trichloroethylene was estimated to be 4 mg/kg/h in males and 5 mg/kg/h in females. Metabolized trichloroethylene was assumed to be converted to either free trichloroethanol (90%) or Trichloroacetic Acid (10%). Free trichloroethanol was glucuronidated forming trichloroethanol glucuronide or converted to Trichloroacetic Acid via back conversion of trichloroethanol to chloral (trichloroacetaldehyde). Trichloroethanol glucuronide and Trichloroacetic Acid were then excreted in urine. Gender-related pharmacokinetic differences in the uptake and metabolism of trichloroethylene were minor, but apparent. In general, the PBPK models for the male and female volunteers provided adequate predictions of the uptake of trichloroethylene and distribution of trichloroethylene and its metabolites, Trichloroacetic Acid and free trichloroethanol. The PBPK models for males and females consistently overpredicted exhaled breath concentrations of trichloroethylene immediately following the TCE exposure for a 2- to 4-h period. Further research is needed to better understand the biological determinants responsible for the observed variability in urinary excretion of trichloroethanol glucuronide and Trichloroacetic Acid and the metabolic pathway resulting in formation of dichloroacetic Acid.
Refaat B. Karim - One of the best experts on this subject based on the ideXlab platform.
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Formulation of Trichloroacetic Acid peeling solution: a bibliometric analysis.
Plastic and reconstructive surgery, 2000Co-Authors: Marieke Vossen, J. Joris Hage, Refaat B. KarimAbstract:Since the beginning of this century, Trichloroacetic Acid solutions of various concentrations have been used for chemical exfoliation. These solutions have been prepared by using four different formulas. To prepare a 50% solution, for instance, water may be added to 50 g of Trichloroacetic Acid crystals until 100 ml of solution is obtained (weight-to-volume solution). Alternatively, 50 g of water may be added to 50 g of Trichloroacetic Acid crystals (weight-to-weight solution), or 50 g of Trichloroacetic Acid crystals may be solved in 100 ml of water (weight-plus-volume solution). Finally, a saturated Trichloroacetic Acid solution (or "100% solution") may be diluted by an equal volume of water (dilution). Depending on the method used, these so-called 50% solutions contain 40 to 71 weight-to-volume percentages of Trichloroacetic Acid. From a review of 120 publications on Trichloroacetic Acid peeling that have appeared since 1926, it was concluded that the authors of 87 of these publications (73 percent) did not report their formula for the Trichloroacetic Acid solution. Any one of the four methods was reported to have been used by the 33 authors who did report their formula. Eight of 10 internationally reputed pharmacopeias were found not to include the formula of a Trichloroacetic Acid solution. Proper evaluation of results and prevention of complications of Trichloroacetic Acid chemexfoliation is only feasible if both the concentration and the formula of Trichloroacetic Acid solution are reported by the author. Practitioners who use a Trichloroacetic Acid solution need to establish that the concentration of the solution they apply corresponds with that of the solution reported in the literature.
Stefan Isenmann - One of the best experts on this subject based on the ideXlab platform.
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Strong interference of hemoglobin concentration on CSF total protein measurement using the Trichloroacetic Acid precipitation method
Clinical Chemistry and Laboratory Medicine, 2007Co-Authors: Klas Böer, Stefan Isenmann, Thomas DeufelAbstract:Background: Among other methods, Trichloroacetic Acid precipitation is used to quantify total protein in cerebrospinal fluid (CSF). Methods: We analyzed the influence of hemoglobin on total protein concentration assayed by the Trichloroacetic Acid method and compared the results to the benzethonium chloride method. Results: Four CSF samples were spiked with different amounts of hemoglobin, leading to overestimation of protein concentration when assayed by the Trichloroacetic Acid method. Using the benzethonium chloride method, measurement of protein concentration was minimally disturbed. In addition, albumin and total protein concentrations were measured in 135 clinical samples. The total protein/albumin ratio remained constant when protein was measured with the benzethonium chloride method, while ratios increased when protein was assayed by the Trichloroacetic Acid method. Conclusions: Strong interference by hemoglobin leads to overestimation of the total protein concentration in CSF when assayed by the Trichloroacetic Acid method and may lead to false conclusions when evaluating the blood-brain barrier.
