Impedance spectroscopy of conductive commercial hydrogels for electromyography and electroencephalography.

In biomedical applications such as the electroencephalogram, electrocardiogram and electromyogram, usually conductive hydrogels are applied to the skin providing a skin-electrode layer, with the aim of lowering contact impedance and improving the signal/noise ratio. It is important to know the electrical behavior of these materials, obtaining reliable values of their conductivity. It can be extracted by the whole cell impedance, which is affected not only by the bulk but also by the surface properties. The aim of the present work is to characterize the impedance of some currently available conductive hydrogels in the frequency range 5 Hz-1 MHz. For this purpose we have designed a novel cell, with silver electrodes, optical detection of the gap and guard ring. In this paper the results are compared with those obtained by means of a commercial cell with stainless steel electrodes, without a guard ring. In order to extract the different contributions of the bulk and the interface, we fitted the experimental data with a very simple model: the bulk properties are described by a single RC-parallel, whereas the interface is represented by a constant phase element.

Production of an egg yolk antibody against Parietaria judaica 2 allergen.

Specific antibodies are essential tools for studying proteins as well as for diagnostic research in biomedicine. The egg yolk of immunized chicken is an inexpensive source of high-quality polyclonal antibodies. The 12-kDa Parietaria judaica 2 allergen was expressed as a fusion protein and was used to immunize Leghorn chickens. In this paper, we show, using 2-dimensional gel electrophoresis and immunoblotting, that chicken antibodies raised against a recombinant allergen can be used to recognize similar proteins from a pollen raw extract. Allergen identity was confirmed by nanoLC-nanospray-tandem mass spectrometry analysis. Our data demonstrate for the first time that a synergistic combination of molecular biology, 2-dimensional PAGE, and use of nonmammalian antibodies represents a powerful tool for reliable identification of allergens.

Impedance spectroscopy of water solutions: the role of ions at the liquid-electrode interface.

We discuss the influence of the ions dissolved in a liquid on the impedance spectroscopy of a cell. Our analysis is performed in the small-voltage regime, where the actual bulk density of ions is only slightly perturbed by the external electric field. In this framework, we show that the presence of the ions can be taken into account by a surface density of charge. The agreement between the theoretical prediction, on the basis of the assumption that the ionic mobility is frequency independent, and the experimental data for the real and imaginary parts of the impedance is fairly good for frequencies larger than 100 Hz. In the low-frequency range, the agreement of the theory with the experiment is rather poor. In this region, the experimental data can be successfully fitted by introducing the impedance of the metal-electrolyte interface, which is accurately represented by Zi = w(i omega)(-nu), where w and nu are two constants, with 0 < nu < 1. From the analysis of the experimental data, we determine w and nu. The theoretical predictions of our model are in good agreement with the experimental data in the investigated frequency range.

Covalent binding of 15-deoxy-delta12,14-prostaglandin J2 to PPARgamma.

Since 15-deoxy-delta(12,14)-prostaglandin J(2) (15dPGJ(2)) has been identified as an endogenous ligand of PPARgamma thus inducing adipogenesis, it has been reported to play active parts in numerous cellular regulatory mechanisms. As 15dPGJ(2) has been shown to covalently bind several peptides and proteins, we investigated whether it also covalently binds PPARgamma. We first observed that after incubation of 15dPGJ(2) with recombinant PPARgamma, the quantity of free 15dPGJ(2) measured was always lower than the initial amount. We then measured the ability of the labeled agonist rosiglitazone to displace the complex PPARgamma(2)/15dPGJ(2) obtained after pre-incubation. We observed that the binding of rosiglitazone was dependent on the initial concentration of 15dPGJ(2). Finally using MALDI-TOF mass spectrometry analysis, after trypsinolysis of an incubate of the PPARgamma(2) ligand binding domain (GST-LBD) with 15dPGJ2, we found a fragment (m/z = 1314.699) corresponding to the addition of 15dPGJ(2) (m/z = 316.203) to the GST-LBD peptide (m/z = 998.481). All these observations demonstrate the existence of a covalent binding of 15dPGJ(2) to PPARgamma, which opens up new perspectives to study the molecular basis for selective activities of PPARs.

Anomalous intensity dependence of optical reorientation in azo-dye-doped nematic liquid crystals.

The intensity dependence of optical nonlinearity in a nematic liquid crystal doped with an azo-dye is investigated. The reorientational part of the nonlinearity changes from self-defocusing to self-focusing character while the intensity passes through the saturation value of trans-cis photoisomerization. This observation, in accordance with previous models, indicates that the optical torque generated by the trans-isomers is of opposite sign than the torque generated by the cis-isomers. At very low intensities a further reorientational nonlinearity was found, which is attributed to light-induced orientational redistribution of adsorbed molecules at the surface.

Analysis of aromatic sulfur compounds in gas oils using GC with sulfur chemiluminescence detection and high-resolution MS.

The analysis of alkylbenzothiophenes (alkyl-BT) and alkyl-dibenzothiophenes (alkyl-DBT) in light cycle oil (LCO) and straight run (SR) gas oils is described. A detailed identification and quantitative analysis of alkyl-BT and alkyl-DBT present in LCO gas oils was carried out using GC-SCD. For the SR gas oils, the simultaneous presence of thiophenic and nonthiophenic compounds does not allow for a selective analysis of thiophenic compounds by GC-SCD. A new method using gas chromatography coupled with high-resolution mass spectrometry (GC-HRMS) is proposed to selectively detect and quantify the alkyl-BT and alkyl-DBT in SR gas oils. The development of the method and comparison of results between GC-SCD and GC-HRMS are presented.

Formation of cryptophanes from their precursors as viewed by liquid secondary ion mass spectrometry.

The formation of cryptophane-A (C1) and the deuterated cryptophanes C2-C6 from their respective precursors P1-P6 in a mass spectrometer ion-source was evidenced by liquid secondary ion mass spectrometry (LSIMS). Mass-analyzed ion kinetic energy experiments performed on the precursor molecular ions suggested that cryptophane formation occurred mainly in the liquid-matrix before desorption rather than in the gas phase. In addition, we observed that the presence of cations, such as lithium or sodium ions, inhibited the formation of the cryptophane molecular ions. In the light of these results we used the LSIMS technique to investigate the formation of the new cryptophanes C7-C13. All the data collected support the idea that a direct comparison can be made between these experimental findings and chemistry in solution.

Environmental quality and sustainability in the province of Reggio Emilia (Italy): using multi-criteria analysis to assess and compare municipal performance.

Sustainability has become an increasingly significant issue, although practical implementation remains difficult. In Italy, promoting sustainability is particularly problematic at the provincial and municipal level, where the lack of resources and expertise, and the effects of uncoordinated policies make it difficult to achieve minimum requirements to make sustainable policies operational. One essential requirement is knowledge of baseline environmental conditions in each municipality. In the province of Reggio Emilia (Northern Italy) Legambiente, an environmental association, launched an initiative called 'Ecopaese' aimed at gathering data on environmental conditions and stimulating local administrations to implement sustainable policies. To this end, the state of the environment in the 45 municipalities within the province has been monitored using 25 indicators. Their values have been used to rank the municipalities by multiple criteria analysis (MCA). The results of this comparative approach provide information about the level of sustainability attained in the province as a whole as well as in the single municipalities. It is hoped that it will provide the basis for direct action plans at the provincial level by identifying areas for remedial action, as recommended by Agenda 21, the declaration adopted by many countries attending the Rio Summit in 1992.

Bloch wave approach to the optics of crystals.

The Bloch wave method is used to find the effective permittivity tensor epsilon of periodic liquid crystals and artificial structures whose period p is short with respect to the light wavelength lambda and whose optical properties are defined by a permittivity field epsilon(r). The main role of the multiple scattering within the periodic medium is evidenced, and very general expressions of epsilon, based on expansions in ascending powers of the ratio p/lambda and of the light wave vector k, are found. Such expansions allow to discuss the general properties of epsilon, to clarify the role of the spatial dispersions, i.e., to separate the part of epsilon explicitly depending on k from its k-independent part, and to find some interesting properties of crystals that are (i) periodic in only one direction, or (ii) locally isotropic. Finally, the limits of validity of the macroscopic model are discussed. Within these limits only a few terms of the power expansions are required, and their expressions are explicitly given. The obtained results are also useful to better understand the macroscopic optical properties of solid crystals.

Structural determination of zinc dithiophosphates in lubricating oils by gas chromatography-mass spectrometry with electron impact and electron-capture negative ion chemical ionization.

Pentafluorobenzyl ester derivatives were used to identify zinc dialkyldithiophosphates and diaryldithiophosphates antiwear engine oil additives by GC-electron impact ionization (EI) MS and GC-electron-capture negative ion chemical ionization (ECNCI) MS analysis. GC-EI-MS of the dialkyldithiophosphate-pentafluorobenzyl derivatives afforded characteristic fragment ions corresponding to the cleavage of one and two alkyl radicals. In most cases, information was only obtained on one alkyl chain. Additional and complete information was obtained with retention time indices using synthetic derivatives and with GC-ECNCI-MS analysis. ECNCI afforded characteristic dithiophosphate anions which allowed the determination of the total number of carbon atoms in the alkyl radicals. The diastereoisomer mixtures of 2-hydroxy-sec.-alkyl radicals were completely separated on GC analysis.

Detection of exogenous intake of natural corticosteroids by gas chromatography/combustion/isotope ratio mass spectrometry: application to misuse in sport.

A detailed procedure for the analysis of exogenous hydrocortisone and cortisone in urine by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) is proposed. As urinary levels of hydrocortisone are rather low for GC/C/IRMS analysis, the focus is on the main corticosteroid metabolites, tetrahydrocortisone (THE) and tetrahydrocortisol (THF). Following different solid phase extraction purifications, THE and THF are oxidized to 5beta-androstanetrione before analysis by GC/C/IRMS. Significant differences in delta(13)C per thousand values of synthetic natural corticosteroids and endogenous human corticosteroids have been observed. Therefore, a positive criterion, to detect exogenous administration of synthetic corticosteroids in anti-doping control, is proposed.

Two new alpha chain variants: Hb Boghé [alpha58(E7)His-->Gln, alpha2], a variant on the distal histidine, and Hb CHarolles [alpha103(G10)His-Tyr, alpha1].

The present paper reports two new alpha-globin chain variants: Hb Boghé [alpha58(E7)His-->Gln, alpha2] and Hb Charolles [alpha103(G10)His-->Tyr, alpha1]. Hb Boghé was found in a 12-month-old girl who was treated for malignant histiocytosis at 9 months of age and received a bone marrow transplant from her sister. Hb Boghé was undetectable by isoelectrofocusing and high performance liquid chromatography of hemoglobins. It was only revealed by polyacrylamide gel electrophoresis of globin chains in the presence of urea-Triton X-100 and accounted for 10% of the total hemoglobin. Hb Charolles was detected in a 46-year-old patient who presented with microcytosis and hypochromia. It was easily detected by isoelectrofocusing and high performance liquid chromatography. Hb Charolles accounted for 11% of the total hemoglobin. Characterization of the two hemoglobin variants was achieved by DNA and restriction enzyme analyses. Oxygen equilibrium curves measured on whole blood with Hb Boghé were normal. DNA sequencing revealed the association of Hb Charolles with a common mutation of the alpha2 polyadenylation site: AATAAA-->AATAAG.

Screening urine for exogenous testosterone by isotope ratio mass spectrometric analysis of one pregnanediol and two androstanediols.

We propose a new screening method for testosterone (T) doping in sport. The current method for detecting T administration is based on finding a T to epitestosterone ratio (T/E) in urine that exceeds six. The difficulties with T/E are that T administration does not always result in a T/E>6 and that a rare individual will have T/E>6 in the absence of T administration. Our previous studies reveal that carbon isotope ratio helps to determine the origin of the urinary T because the values for T and its metabolites decrease after the administration of exogenous T. In this study, we present a rapid and efficient screening sample preparation method based on three successive liquid-solid extractions, deconjugation with E. coli beta-glucuronidase after the first extraction, acetylation after the second extraction, and a final extraction of the acetates. The 13C/12C of two T metabolites (5beta-androstane-3alpha,17beta-diol and 5alpha-androstane-3alpha,17beta-diol) and one pregnanediol as endogenous reference (5beta-pregnane-3alpha,20alpha-diol) was measured by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) on 10 ml of urine collected from 10 healthy men before and after T administration. Following T administration, the 13 C/12C of 5beta-androstane-3alpha,17beta-diol diacetate and 5alpha-androstane-3alpha,17beta-diol diacetate declined significantly from -26.2 per thousand to -30.8 per thousand and from -25.2 per thousand to -29.9 per thousand, respectively and the 13C/12C of 5beta-pregnane-3alpha,20alpha-diol diacetate was unchanged. In addition, the ratio of androstanediols to pregnanediol increased in the post-T urines.

Saponins from the stem bark of Filicium decipiens.

Four new saponins have been isolated from the stem bark of Filicium decipiens and identified as 3-O-{beta-D-glucopyranosyl(1-->2)-beta- D-glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)-beta- D-xylopyranosyl (1-->6)]. [4-O-angeloyloxy-alpha-L-arabinopyranosyl(1-->2)-alpha-L- rhamnopyranosyl(1-->2)]}-beta-D-glucopyranosyl gypsogenic acid, 3-O-{beta-D-glucopyranosyl(1-->2)-beta-D- glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)- beta-D-xylopyranosyl(1-->6)] [4-O-angeloyloxy-alpha-L- arabinopyranosyl(1-->2)-alpha-L-rhamnopyranosyl(1-->2)]}-beta-D- glucopyranosyl medicagenic acid, 3-O-{beta-D-glucopyranosyl(1-->2)-beta-D- glucopyranosyl}-28-O-{[alpha-L-arabinopyranosyl(1-->2)] [beta-D-xylopyranosyl(1-->4)]alpha-L-rhamnopyranosyl(1-->2)-4-O-[3'- hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyroyloxy++ +]-beta-D- fucopyranosyl} medicagenic acid and 3-O-beta-D-glucopyranosyl-28-O- {[alpha-L-arabinopyranosyl(1-->2)] [beta-D-xylopyranosyl(1-->4)] alpha-L-rhamnopyranosyl(1-->2)-4- O-[(3'-hydroxy-2'-methyl-butyroyloxy)-3-hydroxy-2-methyl-butyro yloxy]-beta- D-fucopyranosyl} zanhic acid. These structures were elucidated by analysis of 2D-NMR spectra and of electrospray ionization mass spectra.

Oxidative decarboxylation of benzoic acid by peroxyl radicals.

A chemical model based on the thermal decomposition of AAPH (2,2'-azobis(2-amidinopropane) dihydrochloride is used for the production of peroxyl radicals. Peroxyl radicals induces the decarboxylation of [7-13C]benzoic acid and the production of 13CO2, which is measured by gas chromatography-isotope ratio mass spectrometry (GC-IRMS). The decarboxylation depends on temperature, AAPH, and benzoic acid concentrations. The decarboxylation also depends on the presence of oxygen. Electron spin resonance studies are performed to confirm the presence of peroxyl radicals under oxygen and of carbon-centered radicals in the absence of oxygen. Decarboxylation rates are measured in the presence of various antioxidants: ascorbate, dimethylsulfoxide, mannitol, and uric acid. It turns out that the decarboxylation is inhibited by each of these antioxidants. The ratio of decarboxylation rates, with and without the antioxidant, varies linearly with the antioxidant concentration. HPLC and GC-MS analyses of reaction products between benzoic acid and AAPH-derived radicals do not detect the presence of radical substitution products on the aromatic ring or the products derived from benzoic acid. There is no doubt that GC-IRMS is a powerful technique to investigate the effects of peroxyl radicals on benzoic acid. In addition, it is possible to follow the degradation of 13C-labeled chemical targets exposed to peroxyl radicals through the production of 13CO2.

[Strategies for the development of the quality of integrated home care]. / Strategie di sviluppo della qualità dell'assistenza domiciliare integrata.

Home Health Care (HHC) is a strategy to provide holistic care for elderly, chronic and terminal patients and for patients early discharged from hospitals. The aim of this article is to give some advice to ensure social and health integration, coordination of procedures and family participation in HCC. Moreover a framework to ensure organization of a HHC service is required and a guideline to define functions and responsibilities, human and physical resources and procedures to deliver health care is provided. The first stage of a HHC project must be an educational programme for the multidisciplinary team involved in home care. The common education is the strategy to improve Quality of a HHC service, involving medical and social workers in the definition of their own "criteria and standards" for organization, resources and procedures.

[Study of plasma acylcarnitines using tandem mass spectrometry. Application to the diagnosis of metabolism hereditary diseases]. / Etude des acylcarnitines plasmatiques par spectrométrie de masse en tandem. Application au diagnostic des maladies héréditaires du métabolisme.

BACKGROUND: L-carnitine is known to transport long chain fatty acids through the mitochondrial membrane but also to export accumulated acyl-CoA's as acylcarnitine esters. Acylcarnitine identification in body fluids allows the diagnosis of mitochondrial inborn errors especially fatty oxidation defects. Tandem mass spectrometry represents a new method for isolation and identification of acylcarnitines in plasma or in blood spotted onto filter paper (Guthrie cards). MATERIAL AND METHODS: In order to validate our method, we studied 30 plasmas from children affected with 15 different inborn errors of metabolism and five amniotic fluids from fetuses affected with several organic acidurias. Fourty-six samples from children at risk for mitochondrial fatty oxidation disorders have been analyzed. We developed a method of tandem mass spectrometry with liquid secondary ion mass spectrometry using deuterated acylcarnitines as internal standards. RESULTS: This method is very sensitive (detection limit = 2 microM). In all affected patients specific acylcarnitine signals corresponding to the metabolic block were constantly found. This confirms the diagnosis and validates the method. Among the 46 at risk children, four defects of long chain fatty acid oxidation were identified. CONCLUSION: This new method is of great interest especially for the long chain fatty acid oxidation defects. These defects are very difficult to diagnose with classical methods as urinary organic acid profiling. A small amount of plasma (100 microL) or blood spotted onto paper is required. The acylcarnitine profile allows a rapid diagnosis if a dedicated apparatus is available.

Isolation and characterization of inositol sphingophospholipids from Phytophthora parasitica Dastur.

Several inositol sphingophospholipids (ISPL) were isolated from mycelia of Phytophthora parasitica Dastur, a phytopathogenic fungus of carnation. The ISPL structures were determined by fast atom bombardment. All ISPL consisted of ceramides linked to inositol phosphate. We investigated the effect of growth conditions on the ISPL produced in four different media that are commonly used for fungal cultures. We showed that P. parasitica Dastur synthesized four major classes of compounds with molecular weights of M(r) = 751, 807, 835, and 849 containing the 16:1 base and the 16:0 or 20:0 or 22:0 or 22h:1 N-acyl group. The relative abundance of the different ISPL is dependent on growth conditions.

Detection of exogenous hydrocortisone in horse urine by gas chromatography-combustion-carbon isotope ratio mass spectrometry.

A gas chromatography-combustion-isotope ratio mass spectrometry method for confirmation of hydrocortisone abuse in horseracing and equine sports is proposed. Urinary hydrocortisone was converted to a bismethylenedioxy derivative which presents good gas chromatographic properties and brings an extra carbon contribution of only two carbon atoms. Synthetic hydrocortisone has a different 13C abundance from that of natural urinary horse hydrocortisone and the difference is significant, therefore exogenous and endogenous hydrocortisone can be distinguished.