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Wear KA, Stiles TA, Frank GR, Madsen EL, Cheng F, Feleppa EJ, Hall CS, Kim BS, Lee P, O'Brien WD, Oelze ML, Raju BI, Shung KK, Wilson TA, Yuan JR. Interlaboratory comparison of ultrasonic backscatter coefficient measurements from 2 to 9 MHz. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2005; 24:1235-50. [PMID: 16123184 DOI: 10.7863/jum.2005.24.9.1235] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
OBJECTIVE As are the attenuation coefficient and sound speed, the backscatter coefficient is a fundamental ultrasonic property that has been used to characterize many tissues. Unfortunately, there is currently far less standardization for the ultrasonic backscatter measurement than for the other two, as evidenced by a previous American Institute of Ultrasound in Medicine (AIUM)-sponsored interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements (J Ultrasound Med 1999; 18:615-631). To explore reasons for these disparities, the AIUM Endowment for Education and Research recently supported this second interlaboratory comparison, which extends the upper limit of the frequency range from 7 to 9 MHz. METHODS Eleven laboratories were provided with standard test objects designed and manufactured at the University of Wisconsin (Madison, WI). Each laboratory was asked to perform ultrasonic measurements of sound speed, attenuation coefficients, and backscatter coefficients. Each laboratory was blinded to the values of the ultrasonic properties of the test objects at the time the measurements were performed. RESULTS Eight of the 11 laboratories submitted results. The range of variation of absolute magnitude of backscatter coefficient measurements was about 2 orders of magnitude. If the results of 1 outlier laboratory are excluded, then the range is reduced to about 1 order of magnitude. Agreement regarding frequency dependence of backscatter was better than reported in the previous interlaboratory comparison. For example, when scatterers were small compared with the ultrasonic wavelength, experimental frequency-dependent backscatter coefficient data obtained by the participating laboratories were usually consistent with the expected Rayleigh scattering behavior (proportional to frequency to the fourth power). CONCLUSIONS Greater standardization of backscatter measurement methods is needed. Measurements of frequency dependence of backscatter are more consistent than measurements of absolute magnitude.
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Thakur KG, Gopal B. Crystallization and preliminary X-ray diffraction studies of two domains of a bilobed extra-cytoplasmic function sigma factor SigC from Mycobacterium tuberculosis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2005; 61:779-81. [PMID: 16511156 PMCID: PMC1952361 DOI: 10.1107/s1744309105022669] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Accepted: 07/15/2005] [Indexed: 11/10/2022]
Abstract
Sigma factors are transcription-regulatory proteins that bind to RNA polymerase and facilitate promoter recognition. The so-called extracytoplasmic function sigma factors help a bacterium to respond to environmental conditions. Mycobacterium tuberculosis SigC (sigmaC) is an extracytoplasmic sigma factor that is essential for lethality in a mouse model of infection and is conserved in all pathogenic mycobacterial species. This protein consists of two domains that are connected by an approximately 25-amino-acid linker. The N-terminal domain contains the sigma2 DNA-binding motif, whereas the sigma4 motif is located in the C-terminal domain. Native sigmaC did not yield diffraction-quality crystals. However, two of its domains have been cloned, expressed and crystallized: sigmaC2 (12.3 kDa) and sigmaC4 (7.5 kDa). The sigmaC2 crystals belong to the hexagonal space group P6(1), with unit-cell parameters a = b = 85.28, c = 79.63 A, and native X-ray diffraction data were collected from this domain to 2.7 A on an in-house X-ray home source. The sigmaC4 crystals belong to the cubic space group F23, with unit-cell parameters a = b = c = 161.21 A. X-ray diffraction data were collected from this domain to 3.1 A, also on an in-house X-ray source.
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Abstract
After reporting the excellent etching properties of molten Ba(OH)2 8H2O as an etchant, we now report some more new and efficient etchants for CR-39 detector. CR-39 detectors were irradiated with fission fragments and alpha particles with a thin 252Cf source. The irradiated detectors were etched in a number of our newly introduced etching solutions as well as in conventionally used 6 M NaOH at 70 degrees C. The newly prepared etching solutions included NaOH/ethanol and NaOH/1-propanol. Processing conditions were optimized for these etchants. From fission and alpha track diameters, bulk etching velocity (VB), track etching velocity (VT), etching efficiency (eta) and their activation energies were determined and compared with that obtained for 6M NaOH at 70 degrees C.
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Konash A, Magner E. Electrochemically Mediated Reduction of Horseradish Peroxidase by 1,1‘-Ferrocenedimethanol in Organic Solvents. Anal Chem 2005; 77:1647-54. [PMID: 15762568 DOI: 10.1021/ac048438v] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cyclic voltammetry is an efficient means of analyzing the catalytic reduction of H2O2 at immobilized horseradish peroxidase (HRP)-Eastman AQ 55 electrodes in the presence of 1,1'-ferrocenedimethanol as a one-electron reversible cosubstrate. This system was employed to study the kinetics of the reduction of compound II of HRP in a number of organic solvents. An electrocatalytic response was detected in methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, 2-butanone, 1,2-propanediol, acetonitrile, ethyl acetate, and ethylene glycol. Unusual bell-shaped variations of the peak or plateau catalytic current with the substrate concentration were observed in all solvents tested. The results obtained in methanol, acetonitrile, and 1-propanol were analyzed using the model developed by Saveant (Limoges, B.; Saveant, J.-M.; Yazidi, D. J. Am. Chem. Soc. 2003, 125, 9192-9203). The values of k3Gamma0 and K3,M, where k3 = k3,1k3,2/(k3,-1 + k3,2), Gamma0 is the surface concentration of active enzyme, and K3,M = (k3,-1 + k3,2)/k3,1, were determined. The values of k3Gamma0 for the mediated reduction of compound II of HRP in methanol, 1-propanol, and acetonitrile (in the presence of 5% aqueous buffer) were not affected by the solvent dielectric constant but decreased with solvent hydrophobicity. The value of K3,M obtained in methanol was similar to that obtained for [Os(bpy)2pyCl]2+ in aqueous buffer.
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Brandenburg VM, Knackstedt C, Gobbelé R, Graf J, Schröder J, Westerhuis R, Kosinski CM. [Hypokalemic paralysis with thyrotoxicosis]. DER NERVENARZT 2004; 75:1007-11. [PMID: 15060769 DOI: 10.1007/s00115-004-1707-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Hypokalemic periodic paralysis as a complication of thyrotoxicosis (thyrotoxic periodic paralysis) most often occurs in east Asian men. It is characterised by recurrent episodes of flaccid paralysis, hypokalemia, and underlying hyperthyroidism. It needs to be distinguished from sporadic and familial forms of periodic hypokalemic paralysis. No disturbances in the acid-base state and no extracorporal potassium loss are present. We report on the typical case of a young Chinese man presenting with hypokalemic periodic paralysis associated with yet unknown Graves' disease. Intravenous substitution of potassium and oral propranolol were administered. Complete remission was achieved after 10 hours. After medical therapy had normalised thyroid hormone levels, no further hypokalemic paralytic attacks occurred.
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CANELIS M, FARNELL FJ, McGAVACK TH. Clinical experiences in parkinsonism with a new type of antispasmodic, 3-(piperidyl)-1-phenyl-1-cyclohexyl- 1-propanol hydrochloride (artane). Am J Med Sci 2004; 218:655-9. [PMID: 15393992 DOI: 10.1097/00000441-194921860-00007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Arnaud N, Georges J. Cw-laser thermal lens spectrometry in binary mixtures of water and organic solvents: composition dependence of the steady-state and time-resolved signals. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2004; 60:1817-1823. [PMID: 15248955 DOI: 10.1016/j.saa.2003.09.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2003] [Revised: 09/01/2003] [Accepted: 09/01/2003] [Indexed: 05/24/2023]
Abstract
The thermal lens effect obtained in binary liquid systems composed of water and ethanol, propanol and acetonitrile has been investigated. The dependence of dn/dT upon the solvent volume fraction follows polynomials up to sixth order and cannot be precisely predicted using the additive rule. The sensitivity of the thermal lens method upon the addition of organic solvent in water varies as the temperature-dependent refractive index gradient to thermal conductivity ratio of the mixture provided that the signal is sampled correctly. Otherwise, especially when steady-state experiments are carried out, the thermally induced concentration gradient, known as the Soret effect, can change the thermo-optical properties of the solution locally in the irradiated area and produce an additional signal. This effect depends on the solvent and is maximum at low solvent composition. At the critical solvent volume fraction of 0.1-0.15, the Soret component may represent up to 25% of the pure thermal lens signal and has a time constant which is 200-400 times greater than the characteristic time constant of the thermal lens.
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Goroncy-Bermes P. Re: Evaluation of the bactericidal effect of five products for surgical hand disinfection according to prEN 12054 and prEN 12791. Marchetti MG et al. J Hosp Infect 2003;54:63-67. J Hosp Infect 2003; 55:238. [PMID: 14572495 DOI: 10.1016/j.jhin.2003.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Güllmar D, Jaap T, Bellemann ME, Haueisen J, Reichenbach JR. DTI measurements of isotropic and anisotropic media. BIOMED ENG-BIOMED TE 2003; 47 Suppl 1 Pt 1:420-2. [PMID: 12451881 DOI: 10.1515/bmte.2002.47.s1a.420] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The ability to measure different rates of diffusion along different directions is one of the features that distinguish DTI from other imaging methods. It allows to extract and visualize information on tissue microstructure and microdynamics. However, to correctly determine the full diffusion tensor, the so-called b-matrix has to be calculated by taking into account the non-negligible influences of image gradients and cross-terms between imaging and diffusion gradients. In this work validation of this b-matrix correction was investigated by determining self-diffusion coefficients of several isotropic media on a 1.5 T clinical whole-body scanner. To investigate these influences on the measurements of anisotropic media the same experiments were performed with a carrot.
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Tessier PM, Johnson HR, Pazhianur R, Berger BW, Prentice JL, Bahnson BJ, Sandler SI, Lenhoff AM. Predictive crystallization of ribonuclease A via rapid screening of osmotic second virial coefficients. Proteins 2003; 50:303-11. [PMID: 12486724 DOI: 10.1002/prot.10249] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Important progress has been made in recent years toward developing a molecular-level understanding of protein phase behavior in terms of the osmotic second virial coefficient, a thermodynamic parameter that characterizes pairwise protein interactions. Yet there has been little practical application of this knowledge to the field of protein crystallization, largely because of the difficult and time-consuming nature of traditional techniques for characterizing protein interactions. Self-interaction chromatography has recently been proposed as a highly efficient method for measuring the osmotic second virial coefficient. The utility of the technique is examined in this work by characterizing virial coefficients for ribonuclease A under 59 solution conditions using several crystallization additives, including PEG, sodium chloride, ammonium sulfate, and propanol. The virial coefficient measurements show some counterintuitive trends and shed light on the previous difficulties in crystallizing ribonuclease A. Crystallization experiments at the corresponding solution conditions were conducted by using ultracentrifugal crystallization. Using this methodology, ribonuclease A crystals were obtained under conditions for which the virial coefficients fell within the "crystallization slot." Crystallographic characterization showed that the crystals diffract to high resolution. Metastable crystals were also obtained for conditions outside, but near, the "crystallization slot," and they could also be frozen and used to collect structural information.
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Yonemitsu K, Koreeda A, Ohtsu Y, Ng'Walali P, Tsunenari S. [Ethanol concentrations in multi-site sampling blood in forensic autopsy cases--a retrospective analysis over a period of six years (1994-1999) in Kumamoto University]. NIHON HOIGAKU ZASSHI = THE JAPANESE JOURNAL OF LEGAL MEDICINE 2002; 56:248-53. [PMID: 12415832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
Ethanol and n-propanol concentrations in forensic autopsy cases determined in Department of Forensic Medicine, Kumamoto University School of Medicine were reviewed retrospectively. Out of 388 autopsies in 6 years (1994-1999), ethanol was positive in 88 (22.7%) cases. Higher positive rates were observed in bleeding and burning cases compared to other cases. Histograms of the blood ethanol concentrations in all ethanol positive cases had two peaks at 0.1 mg/ml to 0.5 mg/ml and 1.5 mg/ml to 2.0 mg/ml ranges, which indicated that not only an intermediate but also a weak drunkenness level could be a risk factor of being involved in forensic fatalities. There were no differences in mean ethanol concentrations in the blood samples of the right, left and whole heart blood collected from each victim. The femoral blood, however, was slightly higher than those of heart blood. N-Propanol, an indicator for postmortem ethanol production, was detected in 14.7% of stomach contents samples as early as 6 to 12 hours of post mortem intervals, whereas it was not remarkable in urine and femoral vein blood.
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Laska M, Seibt A. Olfactory sensitivity for aliphatic alcohols in squirrel monkeys and pigtail macaques. J Exp Biol 2002; 205:1633-43. [PMID: 12000808 DOI: 10.1242/jeb.205.11.1633] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
The view that primates are microsmatic animals is based mainly on an interpretation of neuroanatomical features, whereas physiological evidence of a poorly developed sense of smell in this order of mammals is largely lacking. Using a conditioning paradigm, we therefore assessed the olfactory sensitivity of three squirrel monkeys (Saimiri sciureus) and of four pigtail macaques (Macaca nemestrina) for a homologous series of aliphatic alcohols (ethanol to 1-octanol) and isomeric forms of some of these substances. In the majority of cases, the animals of both species significantly discriminated concentrations below 1 part per million from the odourless solvent, and with 1-hexanol individual monkeys even demonstrated thresholds below 10 parts per billion. The results showed (i) that both primate species have a well-developed olfactory sensitivity for aliphatic alcohols, which for the majority of substances matches or even is better than that of species such as the rat, (ii) that both species generally show very similar olfactory detection thresholds for aliphatic alcohols, and (iii) that a significant negative correlation between perceptibility in terms of olfactory detection threshold and carbon chain length of both the aliphatic 1-and 2-alcohols exists in both species. These findings support the idea that across-species comparisons of neuroanatomical features are a poor predictor of olfactory performance and that general labels such as `microsmat' or`macrosmat', which are usually based on allometric comparisons of olfactory brain structures, are inadequate to describe the olfactory capabilities of a species. Further, our findings suggest that olfaction may play an important and hitherto underestimated role in the regulation of behaviour in the species tested.
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OOI T, SCHERAGA HA. Structural Studies of Ribonuclease. XIV. Tryptic Hydrolysis of Ribonuclease in Propyl Alcohol Solution*. Biochemistry 2002; 3:1209-13. [PMID: 14229660 DOI: 10.1021/bi00897a004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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66
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Palonen S, Jussila M, Porras SP, Hyötyläinen T, Riekkola ML. Nonaqueous capillary electrophoresis with alcoholic background electrolytes: separation efficiency under high electrical field strengths. Electrophoresis 2002; 23:393-9. [PMID: 11870738 DOI: 10.1002/1522-2683(200202)23:3<393::aid-elps393>3.0.co;2-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effect of high voltage on capillary electrophoresis (CE) separations of anionic analytes in nonaqueous separation media was investigated. Methanol, ethanol, 1-propanol, and 1-butanol were tested as background electrolyte (BGE) solvents. Experiments were carried out with a laboratory-built CE instrument suitable for high-voltage separations. Potentials up to 60 kV were applied with reversed polarity to generate unusually high field strengths (e.g. 2000 Vcm-1) and so achieve fast and efficient separations. Highest separation efficiencies were obtained with propanol as BGE solvent, and the dependency of the efficiency on the separation voltage was more or less linear. With the other alcohols, separation efficiency decreased or remained roughly constant with increasing absolute voltage. The separation efficiencies are discussed in terms of longitudinal diffusion, Joule heating, and analyte interaction with the capillary wall. Capillary preconditioning had a varied effect on the separations in the different BGEs as the BGE and the conditioning process affected the electroosmotic flow (EOF) velocity and direction.
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67
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Varjo SJO, Jussila M, Palonen S, Riekkola ML. Interface for coupling nonaqueous wide-bore capillary electrophoresis with mass spectrometry. Electrophoresis 2002; 23:437-41. [PMID: 11870745 DOI: 10.1002/1522-2683(200202)23:3<437::aid-elps437>3.0.co;2-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A liquid-junction-type interface where a thin spraying capillary is inserted inside the separation capillary was constructed for coupling nonaqueous wide-bore capillary electrophoresis (CE) to mass spectrometry (MS). The robust structure of the interface provided fairly easy capillary handling. The study was carried out with uncoated CE capillaries of 200 and 320 microm inner diameter (ID). 1-Propanol-acetonitrile (80:20 v/v) with acetate electrolyte provided a low conducting medium for CE and good spraying conditions for electrospray ionization (ESI) without sheath-flow and drying gas. Methamphetamine, alprenolol, and levorphanol served as model compounds. Approximate detection limits with the 200 microm ID capillary were 35-265 ng/mL.
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Al-Dirbashi OY, Ikeda K, Takahashi M, Kuroda N, Ikeda S, Nakashima K. Drugs of abuse in a non-conventional sample; detection of methamphetamine and its main metabolite, amphetamine in abusers' clothes by HPLC with UV and fluorescence detection. Biomed Chromatogr 2001; 15:457-63. [PMID: 11746242 DOI: 10.1002/bmc.94] [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: 11/07/2022]
Abstract
In this paper, we report the detection of methamphetamine and its major metabolite, amphetamine, in garments belong to known-abusers. These compounds were extracted from the textile using a mixture of chloroform:propan-2-ol (3:1, v/v), derivatized with 4-(4,5-diphenyl-1H-imidazol-2-yl) benzoyl chloride and separated using a reversed-phase high-performance liquid chromatography. The derivatives were detected by measuring either fluorescence at 440 nm or absorbance at 330 nm. By using 1-methyl-3-phenyl propylamine as an internal standard, calibration curves of spiked textile samples were linear over a wide range with correlation coefficients of 0.997 or better. Detection limits at a signal-to-noise ratio of 3 were less than or equal to 37.3 and 0.4 pg on column for the high-performance liquid chromatography-ultraviolet and -fluorescence detection methods, respectively. Intra- and inter-day variations at high and low concentrations (n > or = 3) were < or =12.7%. The developed methods were successfully applied to the determination of methamphetamine and amphetamine in clothes samples belong to abusers.
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Abstract
Methyl-, ethyl- and propyl-esters of beta-lactoglobulin, alpha-lactalbumin and beta-casein were prepared and then hydrolyzed with trypsin in various conditions. Resulting hydrolysates were analysed by SDS electrophoresis and RP-HPLC. The degree of hydrolysis of esterified samples was generally lower than those of the non-modified proteins. The highest degrees of hydrolysis were obtained at pH 7--8 with native and esterified protein samples. beta-Lactoglobulin propyl ester and beta-casein methyl ester yielded the lowest degrees of hydrolysis. Ethyl- and propyl-esters of beta-casein showed high resistance towards tryptic attack, even after 20 h of hydrolysis. SDS electrophoretic patterns of tryptic hydrolysates of native proteins showed bands corresponding to low molecular weights. Tryptic hydrolysates of esterified proteins showed bands with higher sizes. RP-HPLC profiles of tryptic hydrolysates of esterified samples showed peaks with longer elution times than those obtained with native proteins, indicating the presence of more hydrophobic peptide populations. A peptic pre-treatment improved tryptic action on esterified proteins. It resulted in a better resolution of RP-HPLC profiles and in a complete disappearance of the protein after 20 h tryptic hydrolysis.
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Grillo AO, Edwards KL, Kashi RS, Shipley KM, Hu L, Besman MJ, Middaugh CR. Conformational origin of the aggregation of recombinant human factor VIII. Biochemistry 2001; 40:586-95. [PMID: 11148054 DOI: 10.1021/bi001547t] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aggregation of proteins is a major problem in their use as drugs and is also involved in a variety of pathological diseases. In this study, biophysical techniques were employed to investigate aggregate formation in the pharmaceutically important protein, recombinant human factor VIII (rhFVIII). Recombinant human factor VIII incubated in solution at 37 degrees C formed soluble aggregates as detected by molecular sieve chromatography and dynamic light scattering. This resulted in a corresponding loss of biological activity. Fluorescence and CD spectra of the thermally stressed rhFVIII samples did not, however, suggest significant differences in protein conformation. To identify conformational changes in rhFVIII that may be involved in rhFVIII aggregation, temperature and solutes were used to perturb the native structure of rhFVIII. Far-UV CD and FTIR studies of rhFVIII as a function of temperature revealed conformational changes corresponding to an increase in intermolecular beta-sheet content beginning at approximately 45 degrees C with significant aggregation observed above 60 degrees C. Fluorescence and DSC studies of rhFVIII also indicated conformational changes initiating between 45 and 50 degrees C. An increase in the exposure of hydrophobic surfaces was observed beginning at approximately 40 degrees C, as monitored by increased binding of the fluorescent probe, bis-anilinonaphthalene sulfonic acid (bis-ANS). Perturbation by various solutes produced several transitions prior to extensive unfolding of rhFVIII. In all cases, a common transition, characterized by an increase in the wavelength of the fluorescence emission maximum of rhFVIII from approximately 330 to 335 nm, was observed during thermal and solute perturbation of factor VIII. Moreover, this transition was correlated with an increased association of factor VIII upon incubation at 37 degrees C in the presence of various solutes. These results suggest that association of rhFVIII in solution was initiated by a small transition in the tertiary structure of the protein which produced a nucleating species that led to the formation of inactive soluble aggregates.
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Molina M, Silva M. Rapid determination of fungicides in fruit juices by micellar electrokinetic chromatography: use of organic modifiers to enhance selectivity and on-column high-salt stacking to improve sensitivity. Electrophoresis 2000; 21:3625-33. [PMID: 11271480 DOI: 10.1002/1522-2683(200011)21:17<3625::aid-elps3625>3.0.co;2-k] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A rapid, reliable method for the multiresidue analysis of eight commonly used fungicides by micellar electrokinetic chromatography (MEKC) was developed. Excellent separation of the eight fungicides (carbendazim, metalaxyl, captan, procymidone, folpet, captafol, vinclozolin and iprodione) is achieved within about 10 min by using optimized electrophoretic conditions that include the addition of a mixture of organic modifiers to the running buffer for improved resolution. The sensitivity of the method is enhanced by using an enrichment step that involves on-column high-salt stacking. Limits of detection in the microgram-per-liter region and relative standard deviations from 2.1 to 5.9% are thus obtained for the fungicides without detracting from peak resolution. These results reveal that the high-salt stacking method provides highly improved sensitivity and enables highly flexible adjustment of the selectivity of the separation method. Also, the method surpasses other stacking alternatives used in MEKC and affords routine analyses of fruit juice containing fungicides at trace levels following a straightforward sample treatment. The robustness of the high-salt stacking method as demonstrated in this work makes MEKC methods involving stacking procedures an attractive choice for routine analyses.
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Kang J, Vankeirsbilck T, Van Schepdael A, Orwa J, Roets E, Hoogmartens J. Analysis of colistin sulfate by capillary zone electrophoresis with cyclodextrins as additive. Electrophoresis 2000; 21:3199-204. [PMID: 11001218 DOI: 10.1002/1522-2683(20000901)21:15<3199::aid-elps3199>3.0.co;2-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A method for the quantitative analysis of colistin sulfate by capillary zone electrophoresis is described. Since colistin components have five free amino groups, they tend to adsorb onto the capillary wall and cause peak tailing. It was found that triethanolamine (TEA)-phosphate buffer at pH 2.5 was useful to reduce such adsorption. Methyl-beta-cyclodextrin (M-beta-CD) and 2-propanol (IPA) were found necessary for selectivity enhancement. In order to optimize the separation parameters and predict the method robustness, a central composite design was performed including three variables, namely concentration of M-beta-CD, TEA, and IPA. The effects of capillary length and applied voltage on separation were also investigated. The optimal conditions established were: 140 mM TEA-phosphate buffer containing 5 mM M-beta-CD and 6% v/v IPA, a capillary with 55 cm total length (50 microm inner diameter, 47 cm from inlet to detection window) and 24 kV applied voltage. The method was found to be robust when the variables were changed in the following range: 4-6 mM M-beta-CD, 5-7% v/v IPA, and 130-150 mM TEA. Further, the linearity, limit of detection (LOD), and limit of quantitation (LOQ), as well as repeatability for both colistin A and B were examined and three commercial samples were quantitatively analyzed.
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Cao S, Chen H, Zeng X. [Matrix effects in inductively coupled plasma mass spectrometry by use of organic solvents]. GUANG PU XUE YU GUANG PU FEN XI = GUANG PU 2000; 20:498-500. [PMID: 12945359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Matrix effects arising from ethanol, propanol, glycerol, acetic acid, ethylenediamine and triethanolamine in inductively coupled plasma mass spectrometry have been studied. Addition of ethanol, propanol, glycerol, acetic acid, ethylenediamine and triethanolamine into solution has an enhancement effect on the signal intensity of analyte with ionization potential between 9 and 11 eV. The ethylenediamine and triethanolamine have higher enhancement effect on the signal intensity of Hg than that of ethanol, propanol, glycerol and acetic acid. Addition of ethylenediamine and triethanolamine into solution has a suppression effect on the signal intensity of Pb and Sr. The mechanism of the enhancement or suppression was investigated. The signal enhancement of Hg in the presence of ethylenediamine and triethanolamine is not caused by improved degree of ionization of Hg and nebulization efficiency. The suppression effects of Pb and Sr in the presence of ethylenediamine and triethanolamine are due to decrease of atomization efficiency of these elements. A method for the determination of Hg in the biological standard samples by ICP-MS was developed.
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Martín-Biosca Y, Sagrado S, Villaneuva-Camañas RM, Medina-Hernández MJ. Determination of barbiturates in urine by micellar liquid chromatography and direct injection of sample. J Pharm Biomed Anal 1999; 21:331-8. [PMID: 10703988 DOI: 10.1016/s0731-7085(99)00147-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A liquid chromatographic procedure for the determination of six barbiturates (barbital, diallyl barbituric acid, phenobarbital, butabarbital, amobarbital and pentobarbital) in urine samples is described. The proposed system uses a Spherisorb octadecyl-silane ODS-2 C18 analytical column and a guard column of similar characteristics. The UV detector was set at 240 nm. A study to select adequate composition of the micellar mobile phase for the separation of these compounds in urine samples is performed. Maximum resolution was achieved with a 0.07 M sodium dodecylsulphate-0.3% propanol at pH 7.4 eluent. Limits of detection at 240 nm were ranged between 0.13 microg ml(-1) for diallyl barbituric acid and 2.7 microg ml(-1) for amobarbital. The procedure allows for the determination of these compounds in 20 minutes, it does not require prior a sample preparation step and it can be very useful to the investigation of intoxication.
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Madsen EL, Dong F, Frank GR, Garra BS, Wear KA, Wilson T, Zagzebski JA, Miller HL, Shung KK, Wang SH, Feleppa EJ, Liu T, O'Brien WD, Topp KA, Sanghvi NT, Zaitsev AV, Hall TJ, Fowlkes JB, Kripfgans OD, Miller JG. Interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 1999; 18:615-631. [PMID: 10478971 DOI: 10.7863/jum.1999.18.9.615] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In a study involving 10 different sites, independent results of measurements of ultrasonic properties on equivalent tissue-mimicking samples are reported and compared. The properties measured were propagation speed, attenuation coefficients, and backscatter coefficients. Reasonably good agreement exists for attenuation coefficients, but less satisfactory results were found for propagation speeds. As anticipated, agreement was not impressive in the case of backscatter coefficients. Results for four sites agreed rather well in both absolute values and frequency dependence, and results from other sites were lower by as much as an order of magnitude. The study is valuable for laboratories doing quantitative studies.
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