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L Valat

Publications and source records attributed to L Valat.

3 recordsLinked to original sources

Harmonization of strategies for the validation of quantitative analytical procedures. A SFSTP proposal--Part I.

This paper is the first part of a summary report of a new commission of the Société Française des Sciences et Techniques Pharmaceutiques (SFSTP). The main objective of this commission was the harmonization of approaches for the validation of quantitative analytical procedures. Indeed, the principle of the validation of theses procedures is today widely spread in all the domains of activities where measurements are made. Nevertheless, this simple question of acceptability or not of an analytical procedure for a given application, remains incompletely determined in several cases despite the various regulations relating to the good practices (GLP, GMP, ...) and other documents of normative character (ISO, ICH, FDA, ...). There are many official documents describing the criteria of validation to be tested, but they do not propose any experimental protocol and limit themselves most often to the general concepts. For those reasons, two previous SFSTP commissions elaborated validation guides to concretely help the industrial scientists in charge of drug development to apply those regulatory recommendations. If these two first guides widely contributed to the use and progress of analytical validations, they present, nevertheless, weaknesses regarding the conclusions of the performed statistical tests and the decisions to be made with respect to the acceptance limits defined by the use of an analytical procedure. The present paper proposes to review even the bases of the analytical validation for developing harmonized approach, by distinguishing notably the diagnosis rules and the decision rules. This latter rule is based on the use of the accuracy profile, uses the notion of total error and allows to simplify the approach of the validation of an analytical procedure while checking the associated risk to its usage. Thanks to this novel validation approach, it is possible to unambiguously demonstrate the fitness for purpose of a new method as stated in all regulatory documents.

Chemistry Techniques, Analytical↗

Preliminary attempts to biolistic inoculation of grapevine fanleaf virus.

Biolistics has been studied to inoculate grapevine fanleaf virus (GFLV), a Nepovirus, to its natural woody host, Vitis sp., and its herbaceous host, Chenopodium quinoa. At first, bombardment conditions for in vitro and greenhouse grown plants were set using the uidA reporter gene. The infectious feature of the cartridges was then evaluated by studying infection of C. quinoa plants. Systemic infection was obtained with either GFLV particles or RNA extracts in experimental conditions which gave also the highest transient uidA gene expression. Concerning grapevine, our results indicate that extrapolation to this plant is difficult. In only 1 out of 8 independent bombardment experiments done with GFLV and 41B, we were able to detect the virus in freshly bombarded leaves. Similarly, later after bombardment, Pol mRNAs were detected once, at days 7 and 14 only. Incubating the plants in darkness, as suggested in the literature, or using Rupestris Saint Georges, an indicator for GFLV presence, did not yield any improvement. Finely, our observations suggest that detection of GFLV in bombarded grapevine tissues by immunological or molecular techniques remains a limiting factor, probably due to an excess of inhibitory compounds released during the biolistic process.

Base Sequence↗

GFLV replication in electroporated grapevine protoplasts.

Grapevine fanleaf virus (GFLV), responsible for the economically important court-noué disease, is exclusively transmitted to its natural host in the vineyards through Xiphinema nematodes. We have developed direct inoculation of GFLV into grapevine through protoplast electroporation. Protoplasts were isolated from mesophyll of in vitro-grown plants and from embryogenic cell suspensions. Permeation conditions were determined by monitoring calcein uptake. Low salt poration medium was selected. Electrical conditions leading to strong transient gene expression were also tested for GFLV inoculation (isolate F13). GFLV replication was detected with either virus particles (2 µg) or viral RNA (10 ng) in both protoplast populations, as shown by anti-P38 Western blotting. Direct inoculation and replication were also observed with Arabis mosaic virus (ArMV), a closely related nepovirus, as well as with another GFLV isolate. These results will be valuable in grapevine biotechnology, for GFLV replication studies, transgenic plant screening for GFLV resistance, and biorisk evaluation.

Journal Article↗