Biomedical subjects

G Lognay

Publications and source records attributed to G Lognay.

8 recordsLinked to original sources

PubMed2006

Nematode infection and reproduction in transgenic and mutant Arabidopsis and tobacco with an altered phenylpropanoid metabolism.

Transgenic and mutant Arabidopsis and tobacco plants with altered phenylpropanoid metabolism were infected with the plant parasitic root knot nematode Meloidogyne incognita to assess the effect of the transgene or mutation on nematode infection and reproduction. Modifications in the lignin biosynthetic pathway which alter lignin composition in roots affected reproduction. In Arabidopsis with increased levels of syringyl lignin, reproduction was lower than in wild-type plants, while in tobacco with reduced levels of syringyl lignin, life cycle progression was stimulated. Overexpression of a MYB transcription factor of phenylpropanoid metabolism in tobacco significantly stimulated reproduction of M. incognita, while overexpression of L-phenylalanine ammonia-lyase had no effect. Arabidopsis transparent testa mutants with deficiencies in flavonoid pathway enzymes did not affect reproduction of M. incognita in the present infection tests.

Animals↗

PubMed2006

Estimating fatty acid content in cow milk using mid-infrared spectrometry.

Interest in the fatty acid composition of dairy products is increasing; however, the measurement of fatty acids requires using gas-liquid chromatography. Although this method is suitable, it involves a time-consuming procedure, expensive reagents, and qualified staff. By comparison, the mid-infrared (MIR) spectrometry method could be a good alternative for assessing the fatty acid profile of dairy products. The objective of this study was to explore the calibration of MIR spectrometry for estimating fatty acid concentrations in milk and milk fat. Estimated concentrations in milk fat were less reliable than those for the same fatty acids in milk. Results also showed that when the fatty acid concentrations in milk increased, the efficiency of the infrared analysis method in predicting these values simultaneously increased. Selected prediction equations must have a high cross-validation coefficient of determination, a high ratio of standard error of cross-validation to standard deviation, and good repeatability of chromatographic data. Results from this study showed that the calibration equations predicting 12:0, 14:0, 16:0, 16:1cis-9, 18:1, and saturated and monounsaturated fatty acids in milk could be used. Thus, with its potential for use in regular milk recording, this infrared analysis method offers the possibility of assessing and improving the quality of milk produced. Indeed, it enables the fatty acid composition in milk to be estimated for each cow and the estimates to be used as indicator traits to determine the genetic values of underlying fatty acid concentrations. The knowledge of these genetic values would open up opportunities for animal selection aimed at improving the nutritional quality of cow milk.

Animals↗

PubMed2005

New model for performance prediction in fixed-bed reactors based on the approach of the unused bed zone.

In the present study a practical model useful for designers dealing with pilot scale reactors for pollutant control has been developed. Investigations were undertaken for a single-component lead study on New Zealand clinoptilolite at the temperature of 25+/-1 degrees C. Fifteen runs under different operating conditions such as particle characteristics (expressed as d*(p)/D), column geometry (as l*/D) and flow speed (as R*e) have been performed. The results were interpreted by a response surface method (RSM) from which an equation giving the unused bed zone (UBZ) was obtained. From those dimensionless parameters, a sequence of contour plots was drawn, making it easy for a designer to choose optimum design parameters while controlling the operation performance. The flow rate (R*e) range was established over the laminar flow conditions from 1 to 8, (l/D*) was extended from 7 to 20 and (d(p)/D*) varied from 3% to 10%. Optimization of performance of the reactor as UBZ could vary from 10% to 40% of the material operating capacity.

Bioreactors↗

PubMed2005

Potential use of essential oils from Cameroon applied as fumigant or contact insecticides against Sitophilus zeamais Motsch. (Coleoptera: Curculionidae).

Essential oils from seven plants species currently found in Cameroon were extracted by steam distillation and tested for their insecticidal activities against Sitophilus zeamats Motsch. Responses varied with the test applied and the plant species. For the contact toxicity, the acetone was used in order to dilute the pure essential oil. Formulations of 1% of essential oils of Xylopia aethiopica and Ocimum gratissimum were the most toxic and led to 96 and 98% of mortality respectively after 24 h. There was no death in control (0% of mortality). Fumigation test were done by applying 300 microl of pure essential oils in the bottom of closed 800 ml glass containers. In that case, the essential oil of Hyptis spicigera was the most toxic (fumigant) after 48 hours of fumigation followed by Annona seregalensis and Xylopia aethiopica 96 and 95% of mortality respectively. Some of the essential oils of plant species tested are promising for pest control in farmer granaries. However, further investigations are to be done on formulation and side effects.

Animals↗

PubMed2001

The prevalence of mycotoxins in Kashin-Beck disease.

Mycotoxins are naturally occurring toxic chemical compounds produced by fungi infesting agricultural crops both during their growth and storage. Such secondary metabolites, when ingested, can produce toxic syndromes in humans. As it has been suggested that mycotoxins might be involved in the development of Kashin-Beck disease (KBD), we undertook a survey of barley grains of KBD-affected families and non-affected families in that country. We found, by thin layer chromatography, a hitherto unknown metabolite of Alternaria sp. This was especially common on the barley grains of KBD-affected families.

Alternaria↗

PubMed2001

Effects of allelochemicals from first (brassicaceae) and second (Myzus persicae and Brevicoryne brassicae) trophic levels on Adalia bipunctata.

Three Brassicaceae species, Brassica napus (low glucosinolate content), Brassica nigra (including sinigrin), and Sinapis alba (including sinalbin) were used as host plants for two aphid species: the generalist Myzus persicae and the specialist Brevicoryne brassicae. Each combination of aphid species and prey host plant was used to feed the polyphagous ladybird beetle, Adalia bipunctata. Experiments with Brassicaceae species including different amounts and kinds of glucosinolates (GLS) showed increased ladybird larval mortality at higher GLS concentrations. When reared on plants with higher GLS concentrations, the specialist aphid, B. brassicae, was found to be more toxic than M. persicae. Identification of GLS and related degradation products, mainly isothiocyanates (ITC), was investigated in the first two trophic levels, plant and aphid species, by high-performance liquid chromatography and gas chromatography-mass spectrometry, respectively. While only GLS were detected in M. persicae on each Brassicaceae species, high amounts of ITC were identified in B. brassicae samples (allyl-ITC and benzyl-ITC from B. nigra and S. alba, respectively) from all host plants. Biological effects of allelochemicals from plants on predators through aphid prey are discussed in relation to aphid species to emphasize the role of the crop plant in integrated pest management in terms of biological control efficacy.

Animals↗

PubMed1989

Validation of a quantitative procedure for the extraction of sterols from edible oils using radiolabelled compounds.

The work described in this paper is integrated in an analytical programme organised by the Community Bureau of Reference with the aim of developing reference materials certified for sterol content. Preliminary inter-comparison of methods showed that the level of agreement of the results was insufficient for certification purposes. Errors could occur in the different steps before the final determination by gas-liquid chromatography. It was, therefore, decided to validate a quantitative procedure for the isolation of sterols. A well defined saponification-extraction method was tested using labelled sterols ([3H]cholesterol and [3H]cholesteryl oleate) and radiochemical measurements. The study has shown that total cholesterol recovery reached 100.5 +/- 1.4%, that cholesteryl ester was saponified quantitatively and that there were no appreciable amounts of degradation products. The procedure has been used as the basis for the certification of three reference materials and it has been shown that the saponification and extraction procedure leads to the quantitative recovery of sterols regardless of the nature of the fatty material tested.

Cholesterol↗

PubMedDate not supplied

Dexamethasone bovine pharmacokinetics.

Dexamethasone phosphate (DXM-PHO) is an ester which is quickly hydrolysed by the bovine and the dexamethasone (DXM) plasma half-life was 5.16 h. It has been demonstrated that 54 h after DXM-PHO injection, DXM concentrations were lower than 0.1 mg/ml. Tritiated dexamethasone was also administered twice to an another young bull for metabolite investigation. The elapsed time required to recover, in plasma, half of the radioactivity injected was 8.8 h. Radioactivity recovery in the urine reached 36.4% and 22.6% for the first and the second injections respectively.

Animals↗