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D Perret

Publications and source records attributed to D Perret.

At least 19 recordsLinked to original sources
PubMed2005

Construction of an oilseed rape (Brassica napus L.) genetic map with SSR markers.

We constructed a Brassica napus genetic map with 240 simple sequence repeats (SSR) primer pairs from private and public origins. SSR, or microsatellites, are highly polymorphic and efficient markers for the analysis of plant genomes. Our selection of primer pairs corresponded to 305 genetic loci that we were able to map. In addition, we also used 52 sequence-characterized amplified region primer pairs corresponding to 58 loci that were developed in our lab. Genotyping was performed on six F2 populations, corresponding to a total of 574 F2 individual plants, obtained according to an unbalanced diallel cross design involving six parental lines. The resulting consensus map presented 19 linkage groups ranging from 46.2 to 276.5 cM, which we were able to name after the B. napus map available at http://ukcrop.net/perl/ace/search/BrassicaDB , thus enabling the identification of the A genome linkage groups originating from the B. rapa ancestor and the C genome linkage groups originating from the B. oleracea ancestor in the amphidiploid genome of B. napus. Some homologous regions were identified between the A and the C genomes. This map could be used to identify more markers, which would eventually be linked to genes controlling important agronomic characters in rapeseed. Furthermore, considering the good genome coverage we obtained, together with an observed homogenous distribution of the loci across the genome, this map is a powerful tool to be used in marker-assisted breeding.

Brassica napus↗
PubMed2004

Electron-optical characterization of nano- and micro-particles in raw and treated waters: an overview.

State-of-the-art information is presented on the analysis, by transmission electron microscopy (TEM), of aquatic colloidal particles in the size range of 3 to 500 nm least dimension, with a focus on nanoparticles (1-100 nm). Case studies include selections from both natural waters and waters undergoing treatment. The "species" of nano-particles receiving the greatest attention are: humic substances, polysaccharide fibrils, hydrous iron oxides, viruses, clay minerals, refractory cell debris, and heavy metal agglomerates on biological surfaces. Artifacts and how to both detect and minimize them are outlined. Correlative use of TEM with other imaging techniques is emphasized, along with associated spectroscopy. Noted is the potential of computerized image analysis for quantifying colloids on a "per colloid species" basis, using water samples centrifuged onto electron microscope grids.

Colloids↗
PubMed2002

Analytical electron microscopy as a tool for accessing colloid formation process in natural waters.

Analytical electron microscopy was used to characterize aquatic iron-rich colloids. We focused our attention on a redox transition medium in the drainage water of a peat soil. In the anoxic peat water, observations by transmission electron microscopy and associated energy dispersive analyses (TEM-EDS) highlight the presence of spherical entities (approximately 100-600 nm), containing only traces of iron. The increase of dissolved oxygen concentration favours the formation of iron oxy(hydr)oxides. In the oxygenated drain, particles with the same morphology and size range are present. Statistical TEM-EDS analyses show that they represent the only colloidal form of iron in the drain samples. Nevertheless, although Fe-K peaks appear clearly on EDS spectra, the proportion of iron in these colloids reaches at most 4% at. (whereas C + O > 90% at.). Structural information completes this study. Both electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS) reveal the disparity between element distributions within the drain entities. Iron and calcium are preferably distributed on the outer sphere of the particle, whereas carbon and oxygen follow the theoretical variation of the signal intensity within a plain sphere. The implication of organic matter as nucleation site for iron precipitation is spectacularly demonstrated by the presence of nanometre-sized iron-rich phases highlighted by EELS line scans.

Colloids↗
PubMed2001

Gadolinium in human glioblastoma cells for gadolinium neutron capture therapy.

157Gd is a potential agent for neutron capture cancer therapy (GdNCT). We directly observed the microdistribution of Gd in cultured human glioblastoma cells exposed to Gd-diethylenetriaminepentaacetic acid (Gd-DTPA). We demonstrated, with three independent techniques, that Gd-DTPA penetrates the plasma membrane, and we observed no deleterious effect on cell survival. A systematic microchemical analysis revealed a higher Gd accumulation in cell nuclei compared with cytoplasm. This is significant for prospective GdNCT because the proximity of Gd to DNA increases the cell-killing potential of the short-range, high-energy electrons emitted during the neutron capture reaction. We also exposed Gd-containing cells to thermal neutrons and demonstrated the GdNC reaction effectiveness in inducing cell death. These results in vitro stimulated in vivo Gd-DTPA uptake studies, currently underway, in human glioblastoma patients.

Cell Death↗
PubMed2001

Development of a method based on accelerated solvent extraction and liquid chromatography/mass spectrometry for determination of arylphenoxypropionic herbicides in soil.

A sensitive and specific analytical procedure for determining arylphenoxypropionic herbicides in soil samples, using Ionspray ionization (ISI) liquid chromatography/mass spectrometry (LC/MS), is presented. Arylphenoxypropionic acids are a new class of herbicides used for selective removal of most grass species from any non-grass crop, commercialized as herbicide esters. Previous studies have shown that the esters undergo fast hydrolysis in the presence of vegetable tissues and soil bacteria, yelding the corresponding free acid. The feasibility of rapidly extracting arylphenoxypropionic herbicides from soil by accelerated solvent extraction (ASE) techniques was evaluated. Four different soil samples were fortified with target compounds at levels of 5 and 20 ng/g by following a procedure able to mimic weathered soils. Herbicides were extracted by a methanol/water (80:20 v/v) solution (0.12 M) of NaCl at 90 degrees C. After clean-up using graphitized carbon black (GCB) as absorbent, the extract was analyzed by HPLC/ISI-MS. The effect of concentration of acid in the mobile phase on the response of ISI-MS was investigated. The effects of varying the orifice plate voltage on the production of diagnostic fragment ions, and on the response of the MS detector, were also investigated. The ISI-MS response was linearly related to the amounts of analytes injected between 1 and 200 ng. The limit of detection (signal-to-noise ratio = 3) of the method for the pesticides in soil samples was estimated to be less than 1 ng/g.

Acids↗
PubMed2001

Use of chelating resins and inductively coupled plasma mass spectrometry for simultaneous determination of trace and major elements in small volumes of saline water samples.

For some saline environments (e.g. deeply percolating groundwater, interstitial water in marine sediments, water sample collected after several steps of fractionation) the volume of water sample available is limited. A technique is presented which enables simultaneous determination of major and trace elements after preconcentration of only 60 mL sample on chelating resins. Chelex-100 and Chelamine were used for the preconcentration of trace elements (Cd, Cu, Pb, Zn, Sc) and rare earth elements (La, Ce, Nd, Yb) from saline water before their measurement by inductively coupled plasma mass spectrometry. Retention of the major elements (Na, Ca, Mg) by the Chelamine resin was lower than by Chelex; this enabled their direct measurement in the solution after passage through the resin column. For trace metal recoveries both resins yield the same mass balance. Only Chelex resin enabled the quantitative recovery of rare earth elements. The major elements, trace metals and rare earth elements cannot be measured after passage through one resin only. The protocol proposes the initial use of Chelamine for measurement of trace and major elements and then passage the same sample through the Chelex resin for determination of the rare earth elements. The detection limit ranged from 1 to 12 pg mL(-1). At concentrations of 1 ng mL(-1) of trace metals and REE spiked in coastal water the precision for 10 replicates was in the range of 0.3-3.4% (RSD). The accuracy of the method was demonstrated by analyzing two standard reference waters, SLRS-3 and CASS-3.

Buffers↗
PubMed2001

Aggregation rates of natural particle populations.

In this paper an experimental approach of aggregation in natural suspensions is presented. The suspensions are organic-matter-rich waters sampled in a brook which drains peat areas. The aggregation was conducted on raw samples in three different experiments lasting from 2 to 8 days. The particle size distribution (PSD) in the 0.5-10 microm size range was followed with a laser sizer and appeared to be almost constant along the whole experiment duration. Nevertheless, the volume of particles larger than 10 microm increased steadily, showing that aggregation occured. This appeared to be the consequence of a steady-state aggregation which allowed the removal of the whole particle set within a day. The use of an aggregation model adapted to calculations on PSD allowed estimation of the aggregation efficiency for such suspensions.

Chemical Precipitation↗
PubMed2000

Solid-phase extraction followed by high-performance liquid chromatography-ionspray interface-mass spectrometry for monitoring of herbicides in environmental water.

In this work we developed a sensitive and specific multiresidue method, based on reversed-phase liquid chromatography-mass spectrometry, with an ionspray interface (LC-ISI-MS), for determining 52 of most representative compounds of herbicides in water samples. The procedure used involved passing 0.5 l of surface water, 2 l of ground water and 4 l of drinking water samples, respectively, through a 0.5 g graphitized carbon black (GCB) extraction cartridge. Base-neutral and acid herbicides were differential eluted from GCB cartridge and follow analyzed by HPLC-ISI-MS apparatus. A conventional 4.6-mm-ID reversed-phase LC C18 column, operating with a mobile phase flow-rate of 1 ml/min, was used to chromatograph the analytes. A flow of 100 microl/min of the column effluent was diverted to the ISI source. The study demonstrates the sensitivity of the technique, with detection limit under 10 ng/l in drinking water samples. Performance data for the method such as recovery and precision are also reported.

Chromatography, High Pressure Liquid↗
PubMed1998

Determination of arylphenoxypropionic herbicides in water by liquid chromatography-electrospray mass spectrometry.

A very sensitive and specific analytical procedure for determining arylphenoxypropionic herbicides in aqueous environmental samples, using pneumatically assisted electrospray (ESI) liquid chromatography-mass spectrometry (LC-MS) is presented. Arylphenoxypropionic acids are a new class of herbicides used for the selective removal of most grass species from any nongrass crop. These herbicides are commercialized as herbicide esters. It has been shown that the ester derivatives undergo fast hydrolysis in the presence of vegetable tissues and soil bacteria, yielding the corresponding free acid. The analytical procedure involves passing 1l of surface or ground water and 2l of drinking-water samples, through a 0.5-g graphitized carbon black (GCB) extraction cartridge. A conventional 4.6-mm I.D. reversed-phase LC C18, operating with a 1 ml/min mobile phase flow-rate, was used for chromatographing the analytes. A flow of 200 microliters/min of the column effluent was diverted to the ESI source. The ESI source was operated in positive-ion mode for neutral pesticides and in negative-ion mode for acid pesticides. For ion-signal optimization, the effect of the concentration of the acid in the mobile phase on the response of the ESI-MS detector was investigated. By evaluating the specificity and sensitivity of the method, the effects of varying the orifice plate voltage on the production of the diagnostic fragment and the response of the MS detector were also investigated. For the analyte considered, the response of the mass detector was linearly related to the amount of the analyte injected between 1 and 200 ng. In all cases, recoveries of the analytes were better than 91%. The limit of detection (signal-to-noise ratio = 3) of the method for the pesticides considered in drinking water samples was estimated to be about 3-10 ng/l.

Chromatography, High Pressure Liquid↗
PubMed1998

High sensitivity quantitative analysis of cobalt uptake in rat cerebellar granule cells with and without excitatory amino acids.

We quantified the effect of the excitatory amino acids kainate and glutamate on the uptake of cobalt in primary rat cerebellar granule neurons, by using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). We quantitatively demonstrated that Co2+ uptake, although enhanced by glutamate and kainate also takes place in the absence of excitatory amino acids. We also found that cobalt uptake is not significantly altered by the presence of glutamate receptor competitive or noncompetitive antagonists, indicating that cobalt uptake in granule neurons does not require glutamate receptor stimulation. Our results suggest, therefore, that Co2+ may enter the cell by passive diffusion through the plasma membrane.

Animals↗
PubMed1998

Development of a method based on liquid chromatography-electrospray mass spectrometry for analyzing imidazolinone herbicides in environmental water at part-per-trillion levels.

An evaluation was made of the feasibility of using reversed-phase liquid chromatography-mass spectrometry with an electrospray interface (LC-ESI-MS) to measure traces of imidazolinone herbicides in different natural water samples. The imidazolinones are a significant new class of low-use-rate, reduced-environmental-risk herbicides for the protection of a wide variety of agricultural commodities. The procedure used involved passing 0.5, 1, 2 1 of river, ground and drinking water samples, respectively, through a 0.5 g graphitized carbon black (GCB) extraction cartridge. Analytes were eluted from the GCB surface by 8 ml of a methylene chloride-methanol (80:20, v/v) solution acidified with formic acid, 25 mM. Recovery was higher than 89% irrespective of the aqueous matrix in which the analytes were dissolved. A conventional 4.6 mm I.D. reversed-phase LC C18 column operating with a mobile phase flow-rate of 1 ml/min was used to chromatograph the analytes. A flow of 50 microliters/min of the column effluent was diverted to the ESI source. The effects of acid concentration on ESI-MS detector response in the mobile phase were investigated. The effects on the production of diagnostic fragments produced by varying the orifice plate voltage and the response of the MS detector were also evaluated. For the analyte considered, the response of the mass detector was linearly related to the amount of analyte injected between 1 and 50 ng. The limit of detection (signal-to-noise ratio = 3) of the method for the pesticides considered in drinking water samples was estimated to be about 2-5 ng/l.

Chromatography, Liquid↗
PubMed1996

[Localized rhabdomyolysis after anaphylactic shock caused by suxamethonium].

A young woman without remarkable medical history, experienced a life threatening anaphylactoid reaction after induction of general anaesthesia for an emergency curettage. Hypersensitivity reaction involving IgE antibodies against suxamethonium was proven by positive skin test and detection of specific IgE by radio-immuno assay. After intensive therapy for 2 to 3 hours, the patient exhibited rhabdomyolysis localized on both calves. This complication, which required fasciotomies, did not result in renal failure. Local and general outcome was good. Rhabdomyolysis was due to compartmental ischaemia following shock and local external compression in the lithotomy position.

Adult↗
PubMed1982

Staphylococcus aureus isolated from poultry in Australia. I. Phage typing and cultural characteristics.

The phage typing and cultural characteristics of 574 strains of S. aureus of poultry origin in Australia were examined. With the avian phage set of Shimizu (1979) it was possible to type 74.2% of strains. A number of significant variations in the phage typing patterns of Australian strains compared to those reported from Japan and Europe were observed. A lower proportion of Australian strains were of avian phage group I and a higher proportion of group III. A high proportion of strains were of mixed lytic groups. No locally isolated phages were able to increase significantly the percentage of typeable strains, although four local phages appeared to be of greater value for phage typing poultry strains of S. aureus than some other phages of the avian phage set. The international (human) phage set was of limited value in typing Australian strains of poultry origin although four strains were identified which were indistinguishable from strains of human origin. Using cultural characteristics of the strains in conjunction with phage typing, the Australian strains of S. aureus were assigned to one of three major groups and nine subgroups. A list of typing phages considered to be valuable for use on Australian poultry strains of S. aureus is given.

Animals↗