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Chahboun A, Coratger R, Ajustron F, Beauvillain J, Aimar P, Sanchez V. Comparative study of micro- and ultrafiltration membranes using STM, AFM and SEM techniques. Ultramicroscopy 1992. [DOI: 10.1016/0304-3991(92)90112-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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177
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Burgaud C, Clifton MJ, Sanchez V. The relative importance of transport phenomena in recycling isoelectric focusing. Electrophoresis 1992; 13:128-35. [PMID: 1592042 DOI: 10.1002/elps.1150130127] [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
The various transport phenomena involved in recycling isoelectric focusing are analyzed for their contributions to band spreading so as to find ways of improving the resolution of this liquid-phase protein purification method. A numerical model is proposed that takes into account diffusion, electroosmosis and electrophoretic migration as a function of pH. The electrohydrodynamic effects have so far been neglected in these calculations. The results of these calculations are compared with experimental measurements performed in different chamber geometries, with a variety of proteins and under different operating conditions, always chosen to avoid flow instabilities. This comparison shows that the resolution of this process is greatly impaired if the electroosmotic slip velocity at the wall is not suppressed.
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Clifton MJ, Jouve N, Sanchez V. Influence of buoyancy-driven convection on protein separation by free-flow electrophoresis. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1992; 12:373-383. [PMID: 11536983 DOI: 10.1016/0273-1177(92)90308-k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In free-flow electrophoresis, the stability and reproducibility of the flow field are prerequisites for a satisfactory separation. Due to the presence of the species to be separated and due to mass- and heat-transfer phenomena, non-uniformities in density inevitably appear, both within the carrier buffer and between the carrier buffer and the sample stream. On earth they give rise to buoyancy-driven convection which interferes with the separation. These effects have been quantified by numerical modelling. Agreement has been found between the numerical results and experimental observations.
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Balmann HRD, Burgaud C, Sanchez V. Study of Electrohydrodynamic Phenomena during Purification of Proteins by Continuous Flow Electrophoresis. SEP SCI TECHNOL 1991. [DOI: 10.1080/01496399108050545] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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180
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Walsh TJ, Hathorn JW, Sobel JD, Merz WG, Sanchez V, Maret SM, Buckley HR, Pfaller MA, Schaufele R, Sliva C. Detection of circulating candida enolase by immunoassay in patients with cancer and invasive candidiasis. N Engl J Med 1991; 324:1026-31. [PMID: 2005939 DOI: 10.1056/nejm199104113241504] [Citation(s) in RCA: 191] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Invasive candidiasis is a major nosocomial infection that is difficult to diagnose. Few biochemically defined markers of invasive candidiasis are known. Initial findings suggested that the presence of candida enolase in the blood may be a novel marker for invasive candidiasis. METHODS We tested 170 patients at high risk for invasive candidiasis for candida enolase antigenemia. All the patients had cancer and neutropenia. We detected antigen using a double-sandwich liposomal immunoassay for candida enolase in serially collected serum samples. Invasive candidiasis was proved by finding candida species in deep nonmucosal tissue, blood cultures, or both. Antigen testing was performed with the investigator blinded to tissue or culture diagnosis. RESULTS Among 24 patients with proved invasive candidiasis, 149 serum samples were tested for enolase antigenemia; 80 were positive and 69 negative (sensitivity per sample, 54 percent). Multiple sampling improved the detection of antigenemia, which was found in 11 of 13 proved cases of deep tissue infection (85 percent) and in 7 of 11 proved cases of fungemia (64 percent). Specificity was 96 percent as measured against control groups including patients with mucosal colonization, bacteremia, and other deep mycoses. Antigenemia was detected in the absence of fungemia in 5 cases of deep tissue candidiasis, but was not detected in 6 cases of fungemia alone. CONCLUSIONS Candida enolase antigenemia is a novel marker for invasive candidiasis. It may be a useful indicator of deep infection in patients with cancer and neutropenia and may complement the diagnostic usefulness of blood cultures.
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181
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Balmann HD, Sanchez V. An Experimental Device to Visualize a Protein Stream during Continuous Flow Electrophoresis. SEP SCI TECHNOL 1991. [DOI: 10.1080/01496399108050461] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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182
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Clifton MJ, Jouve N, de Balmann H, Sanchez V. Conditions for purification of proteins by free-flow zone electrophoresis. Electrophoresis 1990; 11:913-9. [PMID: 2079037 DOI: 10.1002/elps.1150111106] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The separation of proteins by free-flow zone electrophoresis is generally impaired by a number of secondary effects which cause spreading of the protein streams with resultant loss in resolution. A strategy is outlined, based on experimental observations and numerical modeling, which allows the operating conditions and separation chamber dimensions to be chosen so as to obtain complete separation of two proteins of known mobility. This approach takes into account some dispersive phenomena such as molecular diffusion, electroosmosis and residence time gradients. In some cases, the right operating conditions cannot be achieved on earth and electrophoresis separations in microgravity may then be justified.
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183
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Strichartz GR, Sanchez V, Arthur GR, Chafetz R, Martin D. Fundamental properties of local anesthetics. II. Measured octanol:buffer partition coefficients and pKa values of clinically used drugs. Anesth Analg 1990; 71:158-70. [PMID: 2375517 DOI: 10.1213/00000539-199008000-00008] [Citation(s) in RCA: 218] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Because local anesthetic molecules interact with ion channel proteins embedded in membranes to effect impulse blockade, and because their clinical potency often depends on both vascular absorption and distribution into the tissue surrounding the site of deposition, the ability to partition into these various compartments is an important determinant of local anesthetic action. Therefore, the hydrophobic nature of local anesthetics used clinically was characterized by the octanol:buffer partition coefficients of their charged (P+) and neutral (Po) species. This was accomplished by previously described optical methods in which direct spectrophotometric measurement of both the pH-dependent distribution coefficient (Q) and of the ionization permit calculation of the pKa and partition coefficients. The rates of alkaline hydrolysis of ester-linked molecules also were measured to assess potential interference of such hydrolysis with the physicochemical assays. Results indicate that the hydrophobicity of a local anesthetic is increased by manipulation of the molecular structure at three sites: (a) the aromatic ring; (b) the intermediate linking group; and (c) the tertiary amine. Po for the agents studied was 10(3)-10(5) times greater than P+. Although there is no systematic relationship between hydrophobicity and pKa, the latter is greater with ester-linked (pKa = 8.59-9.30) than with amide-linked (pKa = 7.92-8.21) local anesthetics. All of the charged species, with the exception of bupivacaine, selectively partition into the aqueous environment (P+ less than 1.0). The temperature dependence of partitioning of the local anesthetics, measured at 25 and 36 degrees C, indicates an entropy-driven hydrophobic uptake. Solutions buffered with bicarbonate and including 5% CO2 showed the same local anesthetic partitioning as that of CO2-free solutions, suggesting that potentiation of impulse blockade by CO2 is not due to increased membrane uptake. Correlations of physicochemical properties of local anesthetics with potencies on isolated nerve confirm that the more potent local anesthetics have greater octanol:buffer partition coefficients, and that the ester-linked local anesthetics are more potent than their amide-linked counterparts having the same hydrophobicities. The correlations of structure with potency also suggest that the extracellular protonated species may contribute to impulse blockade.
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184
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Sanchez V, McNair HM. Indirect Conductivity Detection in Size-Exclusion Chromatography of Small Molecules. J Chromatogr Sci 1990. [DOI: 10.1093/chromsci/28.8.437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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185
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Lopez JR, Sanchez V, Lopez I, Ryan JF, Mendoza M, Sreter FA, Allen PD. The effects of extracellular magnesium on myoplasmic [Ca2+] in malignant hyperthermia susceptible swine. Anesthesiology 1990; 73:109-17. [PMID: 2360720 DOI: 10.1097/00000542-199007000-00016] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
It is now well established that the pathophysiology of the malignant hyperthermia (MH) syndrome is related to a malfunction of intracellular calcium homeostasis. Magnesium plays important roles in the basic contractile properties of muscle, and many of its actions are antagonistic to those of calcium. The aim of this study was to determine the effectiveness of magnesium sulphate to prevent the MH episode in susceptible animals and correlate this with its effects on the intracellular free calcium [( Ca2+]i). The experiments were carried out using six control (Yorkshire) and ten MH-susceptible crossbred swine (Poland China X Pietrain). After determination of resting concentrations of [Ca2+]i and [Mg2+]i, each animal was given either two iv bolus doses of 50 mg/kg or one iv bolus of 100 mg/kg of MgSO4. The resting [Ca2+]i and [Mg2+]i were determined by means of ion-selective microelectrodes. The resting [Ca2+]i in normal muscle fibers was 0.11 +/- 0.01 microM (mean +/- SEM), whereas in the MH muscles the resting [Ca2+]i was 0.36 +/- 0.01 microM. In neither group was the resting [Ca2+]i modified by MgSO4. This cumulative dose of MgSO4 (100 mg/kg) was not able to prevent the induction of an MH episode by 2% halothane. Although MgSO4 did not directly decrease [Ca2+]i, it did attenuate the increase in [Ca2+]i associated with the syndrome from 7.29 +/- 0.43 microM in untreated animals to 0.84 +/- 0.03 microM in MgSO4 pretreated swine. In addition, the limb rigidity that accompanies this increase in calcium was prevented by MgSO4 pretreatment. Baseline measurements of [Mg2+]i were not different in control and MH-susceptible muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
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Abstract
Pancreastatin is a novel 49-amino acid peptide with a C-terminal glycine amide. The peptide was isolated from porcine pancreatic extracts and shows a structural similarity to chromogranin A. The effect of synthetic porcine pancreastatin on blood glucose levels and hepatic glycogen content was investigated in rats in vivo. Pancreastatin (300 pmol/kg) produced a time-dependent decrease in glycogen content of liver and a slight hyperglycemia. Basal plasma insulin and glucagon levels were not modified by pancreastatin. We suggest that pancreastatin could play a biological role in the glucose metabolism through a glycogenolytic effect.
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Taddei C, Daufin G, Aimar P, Sanchez V. Role of some whey components on mass transfer in ultrafiltration. Biotechnol Bioeng 1989; 34:171-9. [DOI: 10.1002/bit.260340205] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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188
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Bozouklian H, Sanchez V, Clifton M, Marsal O, Esterle A. Electrokinetic bioprocessing under microgravity in France as illustrated by space bioseparation: a programme initiated in France and in cooperation with Belgium and Spain. ADVANCES IN SPACE RESEARCH : THE OFFICIAL JOURNAL OF THE COMMITTEE ON SPACE RESEARCH (COSPAR) 1989; 9:105-109. [PMID: 11537322 DOI: 10.1016/0273-1177(89)90064-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The use of electrokinetic phenomena should prove to be a promising bioseparation technique especially as an application of bioprocessing under microgravity. Therefore, a bioseparation Research and Development programme involving several research teams has been under way for three years in France. Based upon the results of this fundamental research, a programme is now proposed for the development of an automated process chain making it possible to obtain biological macromolecules of high purity under microgravity. This Space Bio Separation programme received the Eureka label at the 6th Ministerial Eureka conference. The project will last six years. It will involve the cooperation of several scientific and industrial partners in France, in Spain and in Belgium. The programme includes the development and validation of three different bioseparation facilities for space.
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Sanchez V, Segedin ER, Moser M, Pallares VS. Role of Lumbar Sympathectomy in the Pediatric Intensive Care Unit. Anesth Analg 1988. [DOI: 10.1213/00000539-198808000-00018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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190
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Sanchez V, Segedin ER, Moser M, Pallares VS. Role of lumbar sympathectomy in the pediatric intensive care unit. Anesth Analg 1988; 67:794-7. [PMID: 3394971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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191
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Biscans B, Alinat P, Bertrand J, Sanchez V. Influence of flow and diffusion on protein separation in a continuous flow electrophoresis cell: computation procedure. Electrophoresis 1988; 9:84-9. [PMID: 3234342 DOI: 10.1002/elps.1150090205] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Continuous flow zone electrophoresis is an efficient method for the non-destructive separation of biological materials in a flowing film of buffer solution in which the constituents of a sample are separated according to their electrophoretic mobilities, under the influence of an electric field. This paper deals with modeling of flow structure of the buffer solution taking into account the effect of electroosmosis, Joule heating and thermal free convection and the forced convection of axial flow. Modeling of diffusion is examined in a second part. The modeling equations and the corresponding boundary conditions are solved by finite difference methods. The various parameters affecting the quality of the fractionation are analyzed.
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Sanchez V, Arthur GR, Strichartz GR. Fundamental properties of local anesthetics. I. The dependence of lidocaine's ionization and octanol:buffer partitioning on solvent and temperature. Anesth Analg 1987; 66:159-65. [PMID: 3813059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The protonation equilibrium and hydrophobic character of lidocaine were characterized by its pKa and the octanol:buffer partition coefficients of the charged (P+) and neutral (Po) drug species. These measurements were accomplished by ultraviolet spectrophotometry of pure lidocaine HCl solutions at different temperatures, ionic strengths, and buffer concentrations. Corroboration of the pKa determination by the potentiometric method and of the partition coefficients by gas chromatography validated the general application of the spectrophotometric technique. The pKa increased with decreasing temperature (7.61 +/- 0.06 at 36 degrees C; 7.94 +/- 0.04 at 26 degrees C, in water; mean +/- SD), increasing ionic strength (8.06 +/- 0.02 at 26 degrees C in 0.165 M NaCl) and increasing buffer capacity (8.28 +/- 0.06 at 25 degrees C in 0.15 M NaCl + 20 mM buffer). Octanol:buffer partition coefficients for both the protonated and the neutral species (expressed as mole fractions) increased upon warning: 0.55 +/- 0.04 and 2666 +/- 202, respectively, at 25 degrees C, and 0.75 +/- 0.09 and 3210 +/- 272, respectively, at 36 degrees C. Ionic strength and buffer concentration had no significant effect on either P value. The increase in pKa at lower temperatures coupled with the decreased partition coefficients resulted in a nearly constant concentration of the protonated species in octanol as the system was cooled, whereas the concentration of the neutral species fell by more than 80%. This finding may explain the large increase in the impulse blocking potency of lidocaine observed upon nerve cooling, if the protonated anesthetic species is the more active form of the drug competing with the neutral species for a common binding site.
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Biscans B, Bertrand J, Sanchez V. Fonctionnement hydrodynamique d'une cellule d'électrophorèse: Elements de calcul. CAN J CHEM ENG 1986. [DOI: 10.1002/cjce.5450640503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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194
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Williams JC, Sanchez V, Scott GH, Stephenson EH, Gibbs PH. Variation in responsiveness of BALB/c sublines and congenic mice to phase I Coxiella burnetii infection and vaccination. Curr Top Microbiol Immunol 1985; 122:189-99. [PMID: 4042676 DOI: 10.1007/978-3-642-70740-7_28] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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195
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Roy S, Papastavros MZ, Sanchez V, Redfield AG. Nitrogen-15-labeled yeast tRNAPhe: double and two-dimensional heteronuclear NMR of guanosine and uracil ring NH groups. Biochemistry 1984; 23:4395-400. [PMID: 6567469 DOI: 10.1021/bi00314a024] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
5N1-Labeled hypoxanthine and 1,3-15N-labeled uracil were synthesized chemically and used to prepare labeled yeast tRNAPhe biosynthetically. Maps (500 MHz) of 15N chemical shift vs. proton chemical shift were obtained, for each ring NH group, by means of INDOR (difference heterodecoupling) and also by means of a proton-observe two-dimensional method involving coherences of forbidden resonances of the NH system. Resonances of GC11, T54-m1A58, GU4, and A psi 31 were confirmed, assigned, or reassigned. psi 39 was found to be in anti conformation, not syn as previously stated. Almost all the uracil NH group resonances could be separated, but most of the GC resonances are too close even in two dimensions to be separately resolved with the observed 20-Hz 15N line width.
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Clifton M, Abidine N, Aptel P, Sanchez V. Growth of the polarization layer in ultrafiltration with hollow-fibre membranes. J Memb Sci 1984. [DOI: 10.1016/s0376-7388(00)80216-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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197
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198
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Miranda H, Fernandez W, Sanchez V. [Keratomycosis. Presentation of 3 cases caused by Fusarium sp]. MYCOPATHOLOGIA ET MYCOLOGIA APPLICATA 1969; 37:179-85. [PMID: 5787930 DOI: 10.1007/bf02051701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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199
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DeBell JT, Sanchez V. Influence of Temperature on the Transmembrane Potential of Ascaris Muscle Cells. J Exp Biol 1968; 48:405-10. [PMID: 5679532 DOI: 10.1242/jeb.48.2.405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. It has been shown that there is an almost linear inverse relationship between the transmembrane potential of the somatic muscle cells of Ascaris lumbricoides and the bath temperature between 38° and 20° C.
2. It has also been shown that the spike frequency reflects these changes, decreasing at a rate of 0.6 impulse/sec./mV.
3. D-Tubocurarine interferes with the response of these cells to thermal changes between 380 and 20° C. but it is ineffective below 20° C.
4. It is proposed that the presynaptic nerve fibres are responsible for the thermal sensitivity of the muscle cells, since the amount of depolarizing neurohormone spontaneously released at the neuromuscular junctions would depend upon the temperature.
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Del Castillo J, Rodriguez A, Romero CA, Sanchez V. Lipid films as transducers for detection of antigen-antibody and enzyme-substrate reactions. Science 1966; 153:185-8. [PMID: 5940361 DOI: 10.1126/science.153.3732.185] [Citation(s) in RCA: 106] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The transverse electrical impedance of thin lipid films separating two aqueous saline solutions containing a small concentration of antibodies or enzymes decreases markedly and reversibly after immunological and enzymatic reactions involving such protein molecules, which presumably are adsorbed to the lipid-water interface.
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